The Coleman 7x7s we had a couple years back for the Scout troop were good out of the box - no seam sealer required. Blew my mind... and it RAINS in the tropics. Reviews Trailrunner posted indicated otherwise for this tent. Commercial seamsealer (available at Dicks) is probably your best bet.

At three pounds you are at the point of diminishing returns (comparing cost vs weight) for a single shelter if you want to stay inside a $60 investment, and assuming you want bug protection and a bottom.

Tarptent's super light Moment is just short of 2lbs (19.75 ozs, according to the website, and note the restriction on rain). You can do better weight wise with a Tarp, but then you sacrifice bug protection unless you can sew. Eureka Solitare and Spitfire are options you can look at in a sporting goods store, but you haven't saved yourself much weight, and you'll have spent more. Plus, you MUST seamseal Eureka tents, or you'll get wet.

Alternately, you can try something like this (someone else here tipped me off about this; I haven't tried it yet, but I'm experimenting)

http://www.imrisk.com/hammock/ultraquarterweight.htm

Good luck, don't sweat it too much, and enjoy the trail.