There are not many options for accommodation on the island, with the small number of visitors. I stayed at the Truk Stop, which also offers diving tours. There is a cheaper hotel just down the road from there but its not on the water and does not offer diving, so you would have to head over to the Truk Stop anyways. The other option is the Blue Lagoon resort on the south side of the island. This is the most expensive option for accommodation, but the dive prices are fairly standard across the dive operators on the island. The other thing to take into consideration if heading to the Blue Lagoon is how far out of town it is, so you will either need to rent a vehicle or buy all supplies and meals from the resort.
There is also only one airline, Continental Airlines, that services the islands so you would either have to fly through Hawaii or Guam to get there. My recommendation would be to get relatively cheaper tickets to Guam, then use airline miles to hop to a couple different island destinations with one stopover included.