A part of my powervalve on my '98 200 broke off, dropped into my lower end, and trashed my transmission. The repair bill was right at $800, for new gears, bearings,seals, and labor. This was out of the question, so, using every bit of patience I had, I waited till I found a whole new engine on e-bay. It was a '91 model, and fit right in, with the exception of the top motor mount, which required new brackets (no biggie). So for less than 1/2 of the estimate of repairing my '98 lower end, I'm riding again, and it has a very similar feel. It's not new, but it got me on the trail, and... the spark plug is easier to get to!
happy trails...
Gordo