Does it have a DR, rear ramp, padded dividers, stock sides, etc.. How much rust? How bad is the floor? Have you looked undeneath? Got any pictures...?  My guess no more than $2500.00 without looking at it.

Looks to be in good shape. Be sure to check the undercarriage framework, lighting, roof, hitch assy and every latch and hinge. In addition to the tires, you might well expect installing new brakes and wheel bearings, if they haven't been previously addressed.

Measure the length and width of the stalls, along with trailer's height, to ensure your horses will fit.

I would guesstimate a price in the $3500 -$5000 range if everything is as good as the photos indicate.

The lower price would reflect having to change out the bearings and brakes along with 5 tires. Nice looking trailer.