Welcome to Houston.
This site gives the location to our pick-a-part junkyards:
http://www.houstonpickapart.com/houston.html
The last time I went a few months ago, I found a z31 and a few 240's at the pick-a-part on Northville. I'd say thats your best bet for cheap parts....
...but if you don't care to pick your part, and can shell out a few extra dollars, you can do a google search and call around. Most of the non pick-a-part junkyards keep an inventory of their cars, and if they don't have what you're looking for, they can most likely send you to someone who does.
Good luck.