I have had five drift boats, all of which were purchased used. I agree with the previous reply that the bottom of the boat will show any prior damage and dents will effect tracking and drag. The coating itself is cheap, easy to replace and should be replaced every one or two years anyways. Check the welds on the inside of the boat and the added components. Anchor pulleys/ locks, anchor rope, oar wrappings/ blades etc. Aluminum is impervious to weatherization so if the style of boat suits you other than the condition of the interior/ exterior paint there isn't much to see. I would check out the trailer more thoroughly though. Logging roads take their toll on trailers and that is a third of the value of the package. Does the trailer have a spare? Tires in good shape? Winch? Rear roller?
For the record, I have owned two Alumawelds and one Willies. There is no comparison in my mind, Willies perform much better! Good luck.
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In the legend of King Arthur, the Fisher King was a renowned angler whose errant ways caused him to be struck dumb in the presence of the sacred chalice. I am no great fisherman, and a steelhead is not the covenant of Christ, but with each of these fish I am rendered speechless.