$400-500 Raft Trailer
I thought I'd share my experience building a raft trailer on the cheap.
I found a used boat trailer on Craigslist for free. I had to pay 45 to drop the boat. To work as a boat trailer I wanted the deck higher and wider, and the wheels to fit inside under the deck.
I used a cheap harbor freight grinder and abrasive blades in a skillsaw to cut the steel. I then rented a 110 volt buzz-box wire feed welder and cut and welded it together as shown in the pics.
IF I CAN, ANYONE CAN USE A WIRE FEED WELDER. Just tweak the settings unitl it works, go slow, and be patient.
I used half-inch MDO plywood for the deck. It's what they make signs out of, and it's coated/fused with a waterproof paper cover. It's bomber, especially if you treat it with deck sealer, or thinned varnish. It's slick enough that I can slide a fully loaded 16' cat on and off if the back of the trailer is in the river.
Still need to figure out a roller and winch, but I'm only into it for between 4 and 5 hundred. Sorry the pics are out of order.