What's the question? Are you asking if you should buy it? To answer that we'd need to know what boat you are intending to put on it, and where you live and plan to use your boat.
That said, here are some general things to consider: Assuming you are planning to use it to transport a V20 boat........
First, it looks like a painted trailer. (It's difficult to tell from the pic if it's aluminum or metal...both look similar in a picture) If it is metal that means that if you so much as bring it near salt water it WILL rust away.
Second, what length is it? It looks short.
Third, what's it's rated weight capacity?
Forth, it needs fenders... they cost about $100 each brand new.
Fifth, just looking at it I'd say that if you plan on transporting a V20 on it it's too small structurally. The longitudinal runners are channel beams rather than box beams. IMHO that greatly reduces it's strength.
Sixth, (and I know some will disagree) It needs brakes.
Seventh, the winch looks "tired" and will probably need to be replaced.
Eighth, Do the brake lights work?
Ninth, you already know about the bunk supports.
Tenth, if the supports are that far rusted, then it's pretty much a given that the bunks will need to be replaced, and you should look at the axle also.
My advice.... find a nice tandem axle Galvanized trailer or if your budget allows it, find a nice Aluminum tandem axle trailer.
