Re: 5150 or 5150 II?
When they first came out, I snatched up one of the first 5150's to be shipped, and paid $650 I think. I still think the 5150 and 6505 have a bigger, more open tone, although my only judgement on the II/Plus is based on store demoing, not wide open like I did with the original versions.
But the Fender manufactured 5150III is a completely different animal, and IMO easily the best out of the 5 incarnations (5150, 5150II, 6505, 6505 plus, 5150III. It's as close to Ecstasy, Diezel, Framus quality as you can get, and the price reflects this. I've demoed the heck out of the Fender 5150III, and it's a great amp - crystal clean to metal meltdown....it does it all really well. The GC Hollywood store actually has a Van Halen room, with 6 stacks in a row. I've gone in there and cranked up a fullstack, running between country, old VH, and Metallica to demo the amp, and it does it all really really well. I used an Andy Summers Tele, VH Charvel, and Gibson Explorer doing the demos, and it sounded spot-on for all 3 styles.