96' would be a CBR600F3... IMHO, for a street bike, the F3/F4/F4i series are some of the most comfortable "sportbikes" there are. They are super easy to ride, lots of used parts around, holds up very well, handles well, etc... "IF" I were to to buy a I-4 sport bike for daily commuting on the street, I'd Look for a nice F4i (2001 - 2006) because (again, in my opinion) it's a MUCH better "commuting" bike than the 600RR is...)
I'd check out
http://cbrforum.com/forum/ - Lots of "F" series bikes/owners over there.
If it's in great condition, well maintained, very clean, with all service records, then $1500 would be a good deal...
But it doesn't sound like from your description...
He said the bike would need a rear brake cable, and a new chain, just guessing but im thinking with the millage where it is this could be the original chain.
Never seen a modern sport bike with a rear brake "cable"... and if it needs a chain, it also need sprockets too... so you're probably looking at around $300 +/- in parts (+ labor unless you do it yourself) for a chain/sprocket set & rear break line. So take that right off the top, also like CDN started to hit on - Has it been in storage for an extended period of time, or has it been ridden (not "started" - but actually ridden) regularly? also how do the "consumable" parts look i.e. tires, brake pads, oil color (Is it clean or dirty), brake fluid color (again clean or dark color), battery date/condition, etc...
Honestly, without looking at it it's very hard to say, but based on your description and assuming a it's in "typical" condition (needs more than what he's telling you), I'd say fair price would be between $1000 - $1200...
I'd recommend looking for a 2001 - 2006 CBR600F4i - it's the best of the "F" series and really the little bit more you'd pay for it, will most likely be cheaper overall.