Looks like an M20 or M30 if I'm reading the decal right. Search "Raleigh M30 bikepedia" and you'll get results like this:
http://www.bikepedia.com/Quickbike/B...=M30&Type=bike
It's a lower end MTB but should be a solid rider. $35 is a very fair price. Upgrades? I wouldn't bother. Frame is likely almost all hi-tensile steel and not worth any upgrades beyond replacing broken parts IMO.