You might check these REI-brand tents out - their stuff is usually as good or better than Sierra Designs. The three person tent for $100 doesn't look bad; a tad heavy at 5 pounds, but roomy; maybe heavier than many of us would carry, but that doesn't mean it can't be carried. Also, I'm not sure whether the fly is full-coverage in the back - if it is, you'd just have to be sure to pitch the back into the wind/rain, since the front isn't full coverage. If the back wall is not full-length, you might have some trouble in a God-hates-hikers, full-out windblown rain - but it should handle the normal rain you're likely to encounter.

Here's the link:
http://www.rei.com/product/731378/rei-camp-dome-2-tent

There are some other tents on tab 3 of the home page (they have 4 or 5 revolving ads there; one is for REI brand tents.)