Small Pokemarts
Potion - 300
Pokeball - 200
Antidote - 100
Small PokeMarts are almost anywhere, any time you need to get something there will be one close by.
Medium Pokemarts
Potion - 300
Super Potion - 700
Pokeball - 200
Greatball - 600
Paralyze Heal - 200
Ice Heal - 250
Full Heal - 600
Burn Heal - 250
Antidote - 100
Awakening -250
Medium Pokemarts are in all the major cities, and they have a lot more of your needs.
Large Pokemarts
Antidote - 100
Awakening - 250
Burn Heal - 250
Ice Heal- 250
Paralyze Heal - 200
Potion - 300
Super Potion - 700
Hyper Potion - 1200
Max Potion - 2500
Revive - 1500
[Region] Mail - 50
TM03 - 5500
TM13 - 5500
TM24 - 5500
TM35 - 5500
TM15 - 7500
You will only find these Pokemarts in the Capital of Each Region, but yet again they have a lot more things to buy.
