try the IoM tourism board - off www.gov.im + the links off this page.
You will find UK and Manx hotels in general considerably more expensive than US hotel - rough rule of thumb for prices is 1 dollar = 1 pound.

The cheapest places are Bed & Breakfast - at one time Douglas was full of them but now a dying breed - these will be around £25/person/night but price varies according to facilities, season etc; hotel rooms vary a lot in price.

A mid-day meal in a manx Pub with a drink will cost you around £10 (18 dollars ) each - evening meals in a better restaurant probably £15 each.