If a standard rectangular cover will work, you would have to go with the 16x36 and have enough deck space around the pool to hold the (small) extra overlap and anchors, then that price is way too high. If you are having it custom cut to fit the pool exactly then that is alright for original loop-loc and very good for ultra-loc.
For comparison you can look at the Hydro Pool & Spa prices without installation.
I paid $1200 for my custom-sized Loop-Loc. Installed it myself in about half a Saturday and a few evenings after work. Installation expense was the cost of one 3/4" hammer drill bit at about $40, and a couple-hundred feet of poly rope to hold the cover over the water while I laid out the anchor positions. No spa or raised beam etc., and the deck was flat all around.
I bought mine through poolcenter.com as it was about the cheapest I found. Really friendly to deal with.