I stayed at the Asia Airport last week. The hotel's online site ( http://www.asiahotel.co.th/ ) does have competitive rates (with the other hotel sites). I booked double occpancy for THB 1650 including 17% tax/service charge. Hotel is a bit scummy (worn carpets, scuffed walls, just seems a bit run down) though and shuttles (at least early morning) only run every hour on the 1/2 hour. Had a free ride there and was worth it for the 0605 NW 28 departure.

I'd be tempted to just slum it in the transit area.

As for REP, note the international departure tax & security fee for foreigners is now USD 25 (it's 18 for Cambodians).