Just had my roof done by a contractor. 68 bundles of shingles, He priced as he would a builder. $5100 including gst. Other wise it would have been $6500. House and 24 X 24 detached garage. One bundle does 33.3 sq ft. Measure your roof area and figure out how many bundles of shingles , that should give you an idea of the cost.
With your description I would guess about $10 K

I just Google Earth measured my roof and I got 2360sq/ft.

The slope isn't very steep. And in the back there is a shingled hangover that runs the entire width of the house over the doors and windows. More than I estimated. Ugh. I might have to sell a nad.