If you need a whole batch of them, an SGI Indigo2 (early rev teal) motherboard can usually be found on the cheap (at least in the US, not sure about elsewhere). They have 12 of the super-heavy duty metal-clip 72pin SIMM sockets on them, too!
I think the one I picked up (which included the 250mhz R4400 processor card -- the item I really wanted) was all of $15 on eBay.
