bigmessowires pointed to a link on mac68k.info in a post above. Just wanted to explain a bit -- I actually designed my own 16 MB IIfx RAM SIMM earlier this year. I only made 9 SIMMs--just enough to give my IIfx 128 MB with a spare. The CAD files (Eagle and Gerbers) are available at that link if anyone's interested. Some of trag's info posted here on 68kmla was useful for finding an affordable way to obtain the chips. The design is my own 4-layer design that I made for fun--not based on trag's at all.

I'm not planning on selling any, but another guy in the linked thread bought a bunch of chips and had a bunch of PCBs made. I think he's planning on making a bunch of them. It might be worth checking with him. At the very least, my 16 MB SIMM design is already out there if it helps speed things up