You would probably have to make your own prop and shaft - not difficult if you have a google for towboatjoe and then go to his masterclass on shafts, then think "smaller". The big problem is payload. Small plastic kits tend to use all of the available weight for the plastic as supplied, which doesnt leave much for anything else. Something like this would probably benefit from a false bottom to hold the working bits plus some ballast to help keep it all upright while keeping the load deck above water. Effectively, you would be sitting it on top of a small submarine.
When looking at fleabay prices, its always worth looking at more conventional suppliers first. There have in the past been lots of cases on here of ebayitis, where auction fever has gripped the participants with the "winner" paying for both the item (at rrp) and a short holiday for the seller.
