LJ is right. Get a few estimates, then call the pros back and ask why A is more than B. And why should you pay more $$$ to A. And so on. A lot of it depends on where you live, the quality of siding you install, and the reputation of the installer. $3 sq. ft. is on the cheap side; $4.50 sq. ft. on the average side.
I suggest you get a neutral color like white, baige, tan, bone, and so on. Stay away from anything 'thinner' than .042 in diameter. If you live in the South, vinyl may not be a good choice. Always install on a smooth, flat surface, or you will void your warranty! Buy an extra square of siding in case you need some for repairs, and such. (Believe me, it's worth $60!) Before you install, look into adding more GFCI outdoor outlets and faucets. (I have 'power' on all 4 sides and water on 3. 1/2 of 1 outlet works from an inside switch too for Christmas lights.) In both these cases, you can buy the outdoor vinyl accessories, place them where you want, and install siding around them, and go back later and drill and install the power or water lines. Consider capping any rake edges, returns, windows, brick molding, etc., with aluminum too. (It adds to the maintenance-free aspect of the house.) BUT, before you cap, clean AND prime the wood. (There's nothing worst than rotting/deteriorated wood to cap. The nails won't hold.)
If you need more 'direction', e-mail me directly. My best to ya and hope this helps.