In the early stage, I didn't lack money until I started DLC with blood and wine. I was really poor
Since this is the week witcher 3, I thought I would give you a quick and simple guide to best weapons and armor at each point in the game.
White orchard: Lv 1 - 4
Weapons: Viper sword set (Lv 1 & 2). Easy the best beginner sword set this takes some work getting around. Both of them need to be crafted and their diagrams are available in two spots - the cemetery near Mill signpost and bandit camp near the ransacked village. The resources needed to craft them might be the hard part but by raiding enough bandit camps, you should be able to obtain both with relative ease.
Armor: None. There is no must-have armor here your basic armor set should suffice you for the entire journey here. However, there is an optional armor that is available called the Temerian armor set (lv 4 and no swords). It is sold by the merchant near the inn who you saved at the beginning of the game. I am calling it optional simply because it is stupid expensive. On your first playthrough, you will barely be able to afford the chest piece by the time you finish the area.
Velen: Lv 4 - 10/11
At the beginning of Velen, your Viper witcher weapons set is more than enough to carry you through this phase of the game. Once you start raiding the west coast of velen, you should have plenty of cash to buy yourself the temerian set.
The later part of the velen is where this gets interesting. As reach the end of Velen quests, you should be around level 10 or 11. If not, wait till you reach this level. Once you are here, you have two armor set you to get yourself. One is the Nilfgaard armor set (no swords) which is capped at lv 10. It is actually cheaper than Temerian set but I personally didn't like it. But since it is so cheap, you can check it out at the quartermaster in Crow's perch. The next is Griffin Armor and weapon set. Now witcher sets need their own post to explain them, but in short - they are set of armor and weapon diagrams scattered all over the region. To get them you need a map. These maps can be bought from blacksmiths, armorsmiths, and quartermasters. The first one can be bought from the blacksmith at midcopse.
Here is a guide to the rest: https://witcherhour.com/vendor-locations-that-sell-scavenger-hunt-maps-to-obtain-witcher-set-gear-bear-cat-griffin/
Once you bought the map and read it in the inventory, the quest should pop up in treasure hunt. Go ahead and happy hunting. Once you obtained all 6 diagrams, same as with Viper witcher weapons, you can get them crafted from a blacksmith. Griffin armor and weapons need a amature blacksmith and armorsmith. Both of whom are avaliable in oxenfurt. The armorsmith is pretty easy to find while the blacksmith is hidding away in the south east corner of the city. Just travel along the outer coast to find him.
Novigrad: Lv 10 - 18
You would have just crafted your griffin armor set, if not this is the best time to do it. It the best armor as of right now.
Once you reach lv 18, you can finally begin hunting for the school of cat gear. The map is bought from the blacksmith in Blackbough in Velen. Alternatively, you can upgrade your griffin armor itself which is yet another treasure hunt. The map should be available from the same vendor from where you bought the earlier griffin maps.
Skellige: Lv 18 - 30 and beyond
Finally we reach Skellige, the best part about it is that you can go ahead and get hold of yourself a cool armor set right away. The undvik armor set (no swords) is easily of the best base game armor set. However, it is also one of the most expensive set so I suggest you start saving up. You can buy this from the armorsmith in Kaer Trolde. Alternatively, you can get your maps for Ursine armor set and other armor set here.
Now is where we get into the late game stuff. There is no clear direction from here as everything is locked above lv 30. Up until Lv 30, the Undvik armor or any of the school armor will provide you all you need. But from here is where the interesting stuff begins. Lv 30 and above is where start getting into the mastercrafted armor sets. However, to start you need to unlock the blacksmith and armorsmith who craft them. For this, complete "swords and dumplings" quest and talk to the armorsmith in crow's perch (another quest opens up). Once you completed their respective quests, you can now craft mastercrafted armor and weapons. More maps can be obtained from the blacksmith you just unlocked and now must be able to get all the three school armor sets.
Kaer Morhen: Lv 16 and above
Now, if you have been buying the maps as I suggested you should have, you would realize that a certain school of wolf armor is locked away in Kaer Morhen. This area doesn' open up until a certain stage into the main quest. Once you get into Kaer Morhen, go ahead and find all the school of wolf gear.
Hearts of stone: Lv 32 and above
There is no particular armor set that is as juicy as the ones before. But you have two sets of armor available to you for trying out. Both are Ofiri amor sets and one can be bought from the Ofiri merchant at upper mill post. The same merchant will send you on a quest to obtain all his diagrams that can be used to craft the other set. Not a lot of difference between the two but they do look dope.
The weapons (Venomous viper witcher sword and Iris) on the other hand can be unlocked only by making a crucial decision at the end of hearts of stone story. No spoilers but just remember to help a certain bandit when in need.
Blood and wine: Lv 34 and above
This expansion introduced quite a few armor and weapon sets. Let's get the witcher set out of the way. Once you reach Beauclair, search for an amorsmith who will ask you to find the grandmaster armor set for all the schools. 5 Treasure hunts open up and you can start hunting down those goodies.
Alternatively, you can get hold of the Toussaint Tourney Knight Armor set. This is yet another craftable set whose diagrams are held in special places called as Hanse Bases, basically bigger and meaner bandit camps. You get only a steel sword from here. You can also buy them from the same armorsmith I mentioned earlier, but they are either master items or magic items. The crafted items are Relic (which I believe are the best version of a weapon).
Now, the best sliver sword called the aerondight can be obtained from a certain lake. Obtaining this sword isn't so straight forward, so I will leave a link on how to obtain it.
Last are the two end game weapons. These are more or less used for NG+. One is the tesham mutna set that you should really not be able to miss. In case you did, go back to the castle and search again.
The last one, Hen Gaidth, is a bit tricky to get. This involves game spoilers, so I am not going to explain it here but will leave a link.
That covers all the best weapons and armor available in the game and the best time to unlock them. Hope you enjoyed it.