sjb-
Check out the website discounttire or discounttiredirect, they usually have good black friday, or more likely cyber monday deals. I have bought from them multiple times. I bought a set of 4 radial trailer tires from them for my 7x23 Legend inline, they are running very nicely and ride well. That is after the misaligned axles from the factory chewed through the original tires way too quickly. Had the new tires dropped shipped from discount directly to the trailer shop, they straightened both axles and installed the new tires, been great ever since. Some trailers come with bias trailer tires, step up to radial trailer tires if possible for a nice improvement in ride quality. Definitely stay with a trailer tire for the reasons mentioned above, sway, durability, etc.
I bought the Taskmaster Contender TTT868, 205/75R15. It's not a Goodyear but its not a cheng shin either. Been on for a couple years now, no issues, run good, no signs of aging, can't complain. I think a fair amount of the trailer tires out there are made overseas. I'd try and stay away from the cheapest bias tires, the saying goes, you get what you pay for.