Where to find 455?

Is it hard to find a Pontiac 455 in a junkyard? And how much can I expect to pay?

I have a 455 blk and possibly a intake and mmaaayybbee a set of heads, email me if you like

Yes, 455s are getting scarce. What exactly are you trying to do with the car? It's not a major ordeal to build a "stroker" (a 400 block with a 4.25" stroke crankshaft) today. Kits are readily available. In truth, 400 blocks are a bit tougher than 455 blocks. The reason for this is the size of the main bearing diameter, and the accompanying housing "bore". The 455 has a 1/4" larger diameter main bearing. As a result, the hole down the middle of the block (main "tunnel") is also 1/4" larger. As the blocks are basically the same casting, that takes out "meat" in a very important area for durability.
If you would like more specific information about the stroker, or the 455, try these sites:
boyleworks.com/musclecars
classicalpontiac.com (Q&A)
performanceyears.com (tech forums)

These are Pontiac-specific sites, where no one will tell you "just put a Chevy in it", because they KNOW about Pontiac power potential.
If you do find a block, but no crank or rods, don't fret. Eagle makes an excellent replacement crank, and you want to discard the original rods, anyway.
Best of luck and welcome to the wacky world of Pontiacs! Chevy guys hate us more than they do the Ford or Dodge crowds. Why? "cuz a Chevy, while some models may be a bit quicker, are still the cheepy car of GM, and Pontiacs are "a cut above.."

Check out the Firebird forum. There is a guy with a Buick 455 for sale!