If you're going to be where you are for a while - like, say, a decade - this is the way to go. I built my own about 15 years ago the same way - 10x12 with vinyl siding for about $1,300 all in. Today ~$1,600 sounds about right. If your living status is likely to change in a few years, then go vinyl as long as it doesn't look like crap. I'd stay away from the Home Depot/Lowe's kits unless you buy some extra lumber to beef it up.