Welcome to PokéCommunity! Register now and join one of the best fan communities on the 'net to talk Pokémon and more! We are not affiliated with The Pokémon Company or Nintendo.
i don't know where you could find them cheap but foolish burial can't be that hard to get since it is only a common Rise of the Dragon lords and since that's been out a while you might be able to find that cheap somewhere.
Umm...yeah, good cards don't usually come cheap, Cyber Valley and Disc certainly not. If you've got any extras of good cards you can try trading those to avoid monetary losses, poke around to see if anyone has extras of disc or valley, but otherwise it's just a matter of accepting the expensiveness. =O