The DMG gas a guideline that has equipment for sale by gp value. DM's can deliberately place such equipment, but we might want to keep in mind that items worth more than 20gp aren't normally available in villages. This includes the following items typically unavailable...
Simple Weapons
This also includes things like healing potions and basic spell scrolls, or any mount other than a mule.
That type of setting with that guideline seems like it could have a large impact at lower levels.
Simple Weapons
- light crossbow
- shortbow
- greataxe
- greatsword
- rapier
- scimitar
- hand crossbow
- heavy crossbow
- longbow
- musket
- pistol
- studded leather armor
- chain shirt
- scale mail
- breast plate
- half plate armor
- Ring Mail
- Chain Mail
- Splint Armor
- Plate Armor
This also includes things like healing potions and basic spell scrolls, or any mount other than a mule.
That type of setting with that guideline seems like it could have a large impact at lower levels.