I got my SSD from Newegg. Their prices and choices are often much better than Best Buy. Here's the one I got (with link):
Corsair F120This is a 120GB SSD drive and a good value for the price, but if you don't want to spend that much here's a similar model that's 40GB:
Corsair F40To put size in perspective: I've been able to capture as many as two and a half dozen high-res/60fps iPi video clips from four cameras, each running several minutes in length in under 20GB. (This was with the SATA; I haven't fully tested my six camera + SSD setup yet, just simple bandwidth tests. Hope to do full tests this weekend if I'm not busy at work.)
Hope this helps.