The snap presses are all pretty similar and pretty much the same price. Although you might check OSDS and see if you can snag their $100 snap press package including press, dies, and snaps.
It's in the remnants/sale section.
Snap Store sells KAM snaps. These snaps fit in any die set EXCEPT the OSDS Industrial. They do fit in OSDS regular dies (I use this combo ALL the time). KAM snaps are available through co-ops and through Serena in China (she's actually cheaper than any co-op I've seen).
OSDS sells their own OSDS snaps - standard and industrial. I have both die sets, and I really like the industrial snaps. The standard are compatible with KAM snaps (ie, you can snap sockets/studs of the two brands together), but the industrial are completely different from anything else out there. I have a sample of standard snaps, but haven't actually used them yet. LOL. The KAM snaps are so cheap from Serena, that that's what I've mostly bought. And I also have the industrial snaps which I love. There are the occasional OSDS industrial snap co-ops out there, but they're not nearly as common as KAM snap co-ops.
Make-It-Snappy has another press, and I'm pretty sure it uses KAM snaps as well as Excel snaps (MIS sells those). The Excel snaps have a regular and a professional version. The professional is kind of like OSDS industrial in that they're really strong and guaranteed for a longer amount of snapping. MIS/Excel snaps fit KAM and OSDS standard dies, but not OSDS industrial dies.
Pretty much, KAM snaps will fit in anything except OSDS Industrial dies. OSDS standard and industrial snaps only fit in their dies (although I'm not 100% sure about MIS dies).
Clear as mud?