just look over it carefully, check the seams and hull to tube bonding, check the transom area for signs of cracks (check it hasnt been painted to hide this).
If its only two years old it should look like new. Thats the hull with no scratches, the transom with no cracks, the engine all nice and shiny with no oil leaks or scratches or dinks in the prop. It should start straight away from cold, it should have a full service history, all the paperwork should be present. All Electronic gadgets should work perfectly. Everything should be present on the trailor and working.
A 2 year old boat has probably had the same working life as a 6 month old car just to put it in perspective. Basically their should be nothing wrong with that boat.
Look on Boats and outboards to see what similar boats have been put up for and take it from there.
Go for a decent trial run that will usually tell if everything is okay.
Best of luck and if your still pondering next week take some photos of the boat and we'll try and give you some more advice.
Check the serial number, engine and boat, against the web sites who publish those of stolen ones, owner should also have proof of purchase. happy hunting