I would ask lots of questions like, Do the lights work? How are the bearings? How old are the tires? How is the winch and strap?
Is all the hardwear to mount the bunks there. Then I would offer $100 to $125 depending on the answers and lack of title. Make them think it's not worth much.
How hard is it to do a home made trailer registration in your state?
Problem with no paper work depends on the state. Here in MI, you have to take it to get it weighed on a certified scale, then take it back to the secretary of state.
On that day, I promised myself I'd never buy a used trailer again.
That would be sold already down here, at that price. You wouldn't have time to ask a message board questions before it sold. If NY is anything like Ga, it is easier to register as homemade, than to transfer reg. numbers.