IF YOU ARE TALKING ABOUT:
POKEMON CENTERS
If you are wondering about the Pokemon Centers, they can be found at any town, city or outside areas (like outside of cave exits).
MEDICINE POCKET
Potions, Revives, Heals, etc. will be unlocked as you continue your adventure throughout the game. You can purchase these at the Poke Mart (blue building) or you can get them using the Dowsing Machine to find poke balls and hidden items.
No, you can not buy any land on Pokemon Heartgold or Soulsilver.
buy it!....
In walmart.
You can not buy Pokemon from the game corner in Pokemon diamond, but you can in heartgold and soulsilver
buy it;)
dork...
Sorry but you can't get jigglypuff in Pokemon pearl. You should trade with someone who has soulsilver or heartgold or you can buy soulsilver or heartgold.
on eBay
buy it at the pokeathelon dome
buy it at the store
You can buy them at the Pokemon mart at the Pokemon league. I buy my timer balls, heal balls, etc. at the Pokemon mart in canalave city
you can buy them at almost any pokmart