As of diamond/pearl/platinum: nowhere, you can only find them. They are mostly found in caves and sometimes laying around.
A good substitute would be the Leppa Berry, which restores the PP of a move by ten. Since you can grow them, they are essentially an infinite free supply, but tedious. You can find Leppa Berries (according to Bulbapedia) in these locations:
Gen III:
Growing on Routes 103, 104, 119, and 123 when the player first arrives there, the Pretty Petal Flower Shop, and the Gentleman in Lilycove City.
Gen IV:
Growing in the Resort Area, Route 209 and 221 when the player first arrives there, Pick a Peck of Colors Flower Shop, Sometimes given from the Berry Master, Often (50% chance) found on wild Clefairy or Cleffa, Rarely (5% chance) found on wild Mr. Mime, Skitty, Delcatty, or Mime Jr., and Given by a Juggler in Violet City in exchange for a Red Shard (HG/SS).
there is lots of max elixers you can find them out in the wild i dont know if you can buy them
u buy it for 1000000
pokemon SHINYGOLD is not a real game. if you want a real pokemon game, there are gold (gameboy color), and heart gold (nintendo DS). you can buy either of those online or you can buy HeartGold from most gaming stores.
no just buy it
Pokemon Gold is no longer being made for the Game Boy Color. You could maybe buy one preowned for $15 or so.
there is lots of max elixers you can find them out in the wild i dont know if you can buy them
in stores and on the ground.
if you have a lot of mony buy elixer then head for tiny wood then clear then by some more
www.ebay.com
You could only buy them in Eba but there is a new version of Pokemon gold its Pokemon Heart gold but its very expensive its $39.99
Sorry but it is not possible to buy them
Buy it at Gamestop.
you can not.
No.
I say gold
Elixer and Max Elixer both refill pp, normal elixer recovers 5pp while max recovers the max pp. The item pp-up will increase any moves pp by 20% of its max pp.
Give it to them and then click use