I have a small collection of reamers that I've bought over the years, sizes that I needed only, no sets.
All of them are Alvord Polk, C-L, Yankee plus a Cleveland expanding reamer set that I don't use much.
The AP reamers, IMHO, are the best. Amazon has AP reamers for great prices. I buy them one at a time since the selection is enormous.
I would only buy new reamers. A dull reamer is not easy to sharpen by hand, and you really need a sharp reamer to cut on size,
or as close as a reamer can cut. Stock removal for the metal you're cutting is also key. Leaving too much or too little can dull a reamer
or ruin your work.
A-P and Yankee have charts on their respective websites. I personally like the Cobalt straight flute chucking reamers.
Spiral flutes work best on cross holes but can be used on straight holes.
I also use end mills to ream some holes or to start holes for reaming.,
when size spec permits. Getting the right pre-ream hole is very important, but like Mikey and others have written, boring is the way to go to get
a good final hole size if it's critical. I bought one import reamer once and never again. They go dull quickly. Ebay is hit and miss. Too many odd sizes.
And don't forget to buy the correct, corresponding pre-ream drill or end mill for the metal you intend to cut.