I found getting prices for new engines to be a bit like pulling teeth. For some reason engine dealers are quite reluctant to give out prices.
My repower was from a chrysler crown flathead 6 gasser to a Volvo-Penta d2-40 diesel. The two engines were vastly different in size and weight. Because of those differences I completely rebuilt the engine compartment (new stringers, new engine beds, fiberglass pan under the engine, new forward side and aft bulkheads with sound insulation, new raw water seacock and strainer, completely new fuel system (tanks, plumbing, dual racor filters, fuel fills, etc.), new cockpit sole panel with sound insulation to replace the old engine box, new coupling on the shaft, repitch and recondition prop, all new wiring, new automatic fire extinguisher with automatic shutdown for the engine, all new engine gauges and shifter/throttle control, new control cables, etc. I had the old engine removed and had the new engine set into the cockpit by a boom truck. I built an a-frame on wheels to move the engine into the house and lower it into the engine compartment. It was a pretty big job. Costs were:
Remove old engine (includes moving boat to and from boat yard on hydraulic trailer - $800
Modifications to engine compartment - $400
New fuel system - $1,000
Wiring, fire suppression, etc. - $600
Engine (including transmission) - $8,900
New exhaust - $400
Engine controls/cables and required cabinet work - $500
Miscellaneous (A-frame, chain fall, specialized tools, etc.) - $400
The total was about $13,000
I did all the labor myself.