I think bikes are like cars: as soon as you drive them off the lot, they depreciate quite a bit. The Jamis has a nice rack AND fenders. Rack and fenders would probably add $60-70 to the cost of the Trek. Jamis are pretty popular here, but I've not seen much about the Commuter line, mostly the Coda line. The frame on the Commuter is unisex, which might make it easier to sell. I also think the less V like frame of the Jamis will give it a more solid feel and be less likely to flex. I also like the green color. The Jamis claims weight of 32 lbs for *some* size. Smaller size might weigh less. The Trek weight is probably similar, but does not include rack and fenders.
Perhaps you could find a nice commuter bike on craigslist for less? If you ad to sell it, you could probably sell it for as much as you paid for it.
Did you test ride each of these bikes? Which one did you like better?