I might be teaching my granny to suck eggs here but...

I took part in group buy on another forum, the guy running it set up a publicly readable Google Docs spreadsheet showing what everyone wanted and how much it would cost. It worked really well as a way of organizing everyone (there were about 20 purchasers in the end) and keeping track of who'd paid / when things had been shipped etc. Might be worth doing the same here now that there's a growing number of us wanting drives.