$600 sounds fair to me, if EVERYTHING is there. Most people end up forgetting to pull the soundbar brackets, which are a little pricey from the dealer. Here's what it should have:
3 windows in a box
door surrounds and knobs for attachig them. Surrounds are in 4 pieces, 6 knobs
top itself, attached to frame
rear window retainer bar, should be rolled up in the top
2 rear window bar retaining clips, I believe they're int he box with the surrounds
2 roll bar brackets - most commonly forgotten piece, without these you're dead in the water, since the top frame attaches to them. If you're Jeep was originally a hardtop only, then you won't have these, they need to be pulled off the Jeep the top came from, which is why they usually get forgotten
4 screws to attached frame to roll bar.
If ANY of it is missing, then it's not worth the price, and you should talk him down based on cost to get it from the dealer and your time to do so.