They are many shops across the map that will sell different goods that can either be weapons, armor, or just cosmetics
Weapon Shops and Yen Shop
The yen shop primarily sells weapons but will also sells other usefull items such as the training weights or spins, the first set of armor can also be bought there
Rare Weapons Shops.The rare weapon shops sells expensive but good weapons with good abilties that are reliable until late mid-game, as usual they cost more, they look cooler, and they do more damage then the weapons in the last shops
Mythical Weapons Shops.
The most expensive weapons by far and the strongest one aswell, this shops sells the best weapons in the game, the weapons this shop sells also need high level requirements compared to the other shops were the weapons needs no level req
Aburt's Abandoned Shack
This shop sells the Golden Armor set, yeah, that's all there is... nothing else