There are plenty of used trailers available. Be sure that what you find has good frame, tongue, torsion or sprung Axle. You want flat bunks or rollers, not "on edge 2 -4" x 8.bunks.
Hubs, bearings wheels are relatively cheap to replace. The frame is not. Brakes--I favor disc. Best are electric over hydraulic, if you have a vehicle which supports the 6 or 7 pin electrical out put. If not you can add a break controller. First in popularity are surge brakes, with an accentuater which which slides as the tow vehicle brakes, and then put pressure in the hydraulic lines. One of two members like the "electric brakes" as used in travel trailer--these are drum brakes. In any case try and wash the trailer and brakes down with fresh water, even if it is only garden sprayer after dunking in salt water.
Craig's list, Boat Trader and similar to find used trailers. Check with nearby trailer shops-often they will have a used or trade in trailer. Just be sure it has the support for a relative flat bottom boat, and is rated for the very minimum of 5000#--5500# is better.
