Sorry mate, I assumed that there would be someone here that knows a spitload more than I
I recently went hunting for a zx7 and bought 99 model. Paid $2.5k but it is nothing flash and has lived by the beach so a little corrosion, slide damage to the usual bar ends, levers, mirrors etc, wasnt too worried as I wanted it more for the track so am going to play with it a little.
It is a great bike to ride with sufficient power without being overwhelming like some of the big bikes. I am really happy with the handling and stoppers although I have only really done one track day and a little on the road.
I found that prices vary a great deal ranging between about $7k and $2.5k. That pretty much depends on kms, condition, service history etc. There are some owners out there that are very flexible on price. check gumtree ( a place i hadnt looked for bikes before but some good prices)
I think when looking at them you wanna look for all the usual issues any motorcycle can have so I guess there is no point telling what you would already know. My engine is a little noisy so have ordered a manual cam chain tensioner to see if it will quieten her down, if not it is an engine out job.
I was directed to this site by a member here and it is a really good site for info on the zx7
http://homepage.ntlworld.com/webzxr/zxr750r/
If I think of anything else I post again
Hope this helps a little
cheers