How much does a DnD players handbook 3.5 and a dungeon masters guidebook 3.5 cost and where can you buy them?

They can cost anywhere from $20-40 each, typically. Check ebay or Amazon.com. You might have luck searching with "3.5 PHB" (Player's Handbook) or "3.5 DMG" (Dungeon Masters Guide)

Alternatively, fan sites like http://www.d20srd.org/ have most (if not all) of the player's handbook information anyway.