The domain prices can be viewed at Godaddy and the like, generally $15 per year. But the hosting comes in various plans, $4 a month for a shared host plan and fewer access rights than other plans. WiKirby has now grown enough to actually break shared hosting, so any startup could make it that far on a shared plan. The plan we are moving to next week, VPS, will cost $50 a month. But we are getting a discount, WHM rights, the move will be done for free, and we have been given a grace period to continue operating on the shared machine until the move takes place, without the limits that were imposed on us.
Bear in mind, the above prices don't include any initial fees that come with it.