It doesn't take much memory, I ran it on a mk2a with ext3 and a few other things running for a while. As far as a cheap GPS, I'm sure there are cheaper ones than the one you found out there. If you happen to want a good one, I've got a GPS16 that I should really sell. It was installed for a year or so for use with GPSapp and worked fine. I think I paid around $200 for it.

-Mike