I have a similar size collection, and I found an inexpensive way to store them using pine storage shelves from a local store that sells unfinished furniture:

http://www.millstores.com/display.ccml?57,0,210579,cc210579,,,Index,cat3C.html

..here's an image: http://www.millstores.com/photosql/17-102.jpg

I have three of these units, each one holds 210-220 LPs, at a cost of $51 each, although I think they were on sale for $40 each when I bought them.

Simply stain them in your favorite shade, or leave them unfinished. They're sturdy, inexpensive, look pretty good, and you can add as many units as needed.