There are limits to how much the same tent design can address all the requirements you named: staying dry, staying both cool and warm in different weather, and resisting high winds.

The more a tent design tries to do everything, the heavier and more expensive it will be. You say you want a three season tent, but seem to be asking it to perform like a four season one. And you want it to be on the moderate-to-cheap end of the price scale. You seem to be asking a lot.

You should probably evaluate where and how you will be using the tent a bit more thoroughly. If you really do need it to perform as well as you indicated, then you'll need to spend considerably more money and spring for a four-season tent like the Stephenson Warmlite tents, or a Hilleberg tent. The chances are very good you really don't need that much tent.

Since you don't want to spend a lot, I would recommend checking out some of the tents that are put on clearance / closeout at a variety of internet sites, such as REI-Outlet or BackCountryClearance. You'll find links to these places on the left edge of this forum page. The chances are good you'll be able to pick up a light and well-designed tent that was originally priced in the $250-$300 range, marked down closer to $150-$180.

In buying a backpack, fit is everything. Some fancy packs may not fit you well. Some cheap packs may fit you like a glove. Be prepared to keep searching until you get one that works for you and your body. Pack "features" are highly overrated. All you need is a bag with some kind of support framework and a padded hip belt to transfer weight. Get that, plus a good fit, and nothing else really matters.

I know it is hard to afford much at age 21, but I would definitely recommend shelling out a bit more for a quality tent and sleeping bag, then economizing like crazy on the rest of your gear. These two items can really make-or-break whether a trip is pleasant or a disaster. A bad purchase here will bite you over and over again.