#1
There's one for sale for $100 locally . Anyone ever use one ?

It has 2 - 100 watt speakers . Maybe from the 90s ? I don't know honestly .

Anyone use one ?
#2
at $100 I say buy it and try it, if you don't like sell it for what you paid for it, or make a bit of profit, you could also sell the speakers and buy new ones to put into the cab if you don't like the tone, but at least you will have a decent cab to work with.
#3
Worth the money. 

With any cabinet, however, you want to pop the back and determine what speakers are actually in it before you pay the money. Always. No exceptions. 
Experiential learning at work here. 
Friend of mine brought home a 4x12, dragged it down into his basement, started playing it, and we noticed a cockroach or two in his basement. He said he'd never had cockroaches. Long story short, when we pulled the back, we found a nest of several million of the suckers, all of whom scattered all over his house to the continual shrieking of his wife. 
On the other side of things, I've opened up  Carvin cabinets to find EV-L's, those british-voiced 100W speakers and V30's when I'd been told there were ordinary Carvin G12s inside. Yay. 

Carvin builds the cabinets themselves well, out of good plywood. Easily as good as anything else out there for lots more money.