My little old utility trailer purchase reminds me of the story "If You Give a Mouse a Cookie".
If you buy a trailer from Craigslist, you need to get it transferred. When you go to DMV you will find that you did not purchase from the last registered owner. Call the seller for information on who sold it to him, but he doesn't have anything. Go back to the seller and have him sign a statement of fact. Back at DMV sign a statement of fact of your own. Good. Now, it's your trailer.
But the lights don't work properly. You signal left and the trailer signals right. If the lights are wired backwards, your son might try to fix them. If your son tries to switch the wiring, the lights stop working at all.
If your trailer lights don't work, you might go to an auto shop to have them fixed. The shop will tell you that the whole thing is a patch up job that really should be replaced, but they can fix it up for now. If the shop does some good patch work on your trailer light wiring, they might offer to check the air in the tires.
If the wiring guys check the air in your tires, they might tell you that 1) the wheels don't match, 2) one is actually are car spare, 3) the other is rotten. You need to replace the wheels and tires. But they don't do that.
If you need your trailer tires replaced, you will make several phone calls to find a shop that carries and hopefully installs trailer wheels.
If you find a shop that carries trailer wheels, they will tell you that they only have one but you can pay for two and go to their warehouse to pick up the other one. They will ask the shop guys if they have time to put them on. When you get out to that shop, they will tell you that the shop guys are too busy, but anyone can change a wheel actually. Or they can recommend the place down the road. Before sending you to go get the 2nd wheel, the tire guys nicely will come out to check your tire size.
If the tire guy looks at your trailer, he will gasp in horror and exclaim that you can NOT drive that trailer any where. The spring hooks or spring hangers or something like that are broken and the whole trailer could drop down onto the wheels if you go over a bump. I was lucky to get to them.
If the trailer wheel guys spots the broken spring hangers, he will send you down the road to another trailer guy who will also gasp in horror.
Instead of loading the trailer up with bikes to ride out in park trails, you will leave the trailer to get an estimate next week. "Don't worry, it's not a big problem."
I don't know if I saved any money or wasted money buying from Craigslist. The cost is adding up. Would it have been better to buy new? I THINK it is still cheaper, but I am not sure.
As Jospeh said Judge Judy said, Sometimes cheap can be pretty expensive.
Someday I will have a trailer. And hopefully my transmission can handle it.