Since you're not in a hurry, spend a little time each week scanning the ads on Craig's List in your area. Then drop by the Harbor Freight store (if you have one) or visit them on line to see what "new" tools of comparable size (forget about quality for now) cost. Demand for tools changes with the season and with what else happens to be on CL at the time. Unless you have one of the "cult classic" tools like an old Delta Uni saw, they'll sell for what the market will pay.
The biggest problem with used tools is that the buyer has no idea what condition they're in or how they've been treated by the previous owner. Almost everything I've purchased off Craig's List that had a power cord had at least one electrical issue, and most of them needed at least a new power cord. Some needed brushes and minor repairs, and once or twice it wouldn't have cost much more for a new one than what I paid for the used one plus the parts for the repair. If you have the literature that came with your tools, make sure to show it to the prospective buyer and have photos of it in your ad. See if you can find a place to purchase parts, and include that info as well.
All of this figures into the price a buyer is willing to pay for a used tool. I find myself much more willing to pay closer to the asking price if the seller has spent the time to clean them up, can show me that they'll run, and demonstrate them doing their intended job. It also helps if the rest of his shop is clean, he drives a well maintained car, and his house doesn't look like a junk yard. I figure if he treats everything else in his life well, chances are he took good care of the tool he's trying to sell to you, too.
Radial arm saws have pretty much been replaced by compound sliding chop saws that take a lot less room. You may end up donating yours, or only getting pennies on the dollar.
Unless it's a well known brand like Speed Air or Ingersol Rand or other Pro level tool, the compressor probably won't bring much more than the HF equivalent. But being 115V at least it'll sell. Nobody wants a 3 phase motor, and many won't fool with 220V, either.
The pricing often doesn't seem fair, especially if you purchased everything new. But keep in mind the money you've saved by not paying someone else to do the work because you had the right tool to do it yourself. And next time you need to buy a tool, see if you can find a used one in good condition. If it's a one time only need, you might be able to sell it for what you paid for it after you're done.
