Great Job. From my experience the best deal is often from the hotel itself (no fees to Booking, Expedia ...), are you including hotels' prices directly in your listing or are you using some OTA's APIs ?
Of the hotels I've viewed, it appears the images are hosted on TravelNow, which (I believe) is owned by Expedia. If that is the case, they are probably using EAN's API for part or all of it.
dev here; yea, we're using EAN for sourcing the hotels that people initially book - but we have many more other OTAs integrated for tracking prices
the way you could look at it is that we try and capture peoples traveling intent with an API which is relatively easy and fast-performing, then we try in our own time to find something better
http://developer.ean.com/