So NADA is saying value for a 2001 challenger 1800 with trailer is low retail $5800 and high is $6600. The cheapest I have seen a rebuilt powerhead for the Mercury 210 jet engine is about $3300 plus freight shipping. So if you do all the work yourself in removing and replacing that powerhead you will be in it for about $4000 just to get it running again with all the other consumable items you need to do the powerhead swap. So then $1000+$4000, and then I bet the canvas needs to be replaced so that will be about $1000-1200, and then tires and work on the trailer another $200-300. So you now have about $6500 into this boat and that is only if the interior vinyl is good! if not add another $1500-2000 for a total of $8000-8500. Boats get expensive real quick, if you want a 18ft boat get one with a I/O 3.0 mercury engine in it, they last longer than one of their jet engines and a rebuilt one is only $2300 vs $3300. And most 18ft boats with a Mercury I/O motor you can pick up cheap in great running condition! I got a 30ft Searay and just maintenance and storage fees cost me anywhere from $3000-8000 per year with me doing all the work, that's not my fuel cost. I restored a little 16ft Bayliner last year, paid $1100 for boat, motor and trailer, cost me $900 for new cockpit and bow canvas (done at a professional shop), $200 for Bimini top, about $500 for all new seats carpet and vinyl doing all work myself on that, and about $300 on engine maintenance and other things to get it into a great running and looking little boat again. So I put $1900 into a running and driving boat that I paid $1100 for so my total was about $3000. I wanted a 18ft boat but I can't fit it in my well with my 30ft without the association complaining it sticks out in the canal so that is why I fixed up my 16ft Bayliner. Boats are a whole different game than jet skis, hope this gives you some insight on boats.