I'd have no problems paying $100 for a 750 in good shape and maybe half that for a 730. $100-$200 for a 730 is on the high side. Depending on the condition of the bike (and the work that has been done), that may be a decent price for the bike or maybe you need to keep looking for a better deal.

As long as the paint is good, the bike is not crashed, and the wheels are reasonably true, a used Trek hybrid is a fine machine. But you will need to be able to do (or learn how to do) your own work on the bike. It's not hard to do.