I've picked used ones off eBay by searching for the specific size, like "1/2" hss reamer". Depending on what you are planning, you may look at an over/under reamer set. Most of the time I'm reaming a hole it's for a dowel pin. Undersize is 0.001" under, so the pin is a press fit. Oversize is 0.001" over, so a slip fit. There are plenty of sets out there for under $125 for 14 reamers (1/8" to 1/2"). Or just do a specific search. I snapped off the tip of my 0.124" reamer but found a replacement with that search.
Bruce