I can’t say what I would pay, because I have one running 310, one 310 ready to be put back together, and three 240’s that need to be gone through. I am out of room for any compressors right now. If I was looking for one to rebuild, I would probably say 100-150 for one like that. Probably 200-225 if that motor was single phase. The 240 is pretty close to the single stage version of the 325.
I paid 80 for one of mine with a tank and no motor. The other two looked great but they came from an auto mechanic shop that couldn’t get them to compress. One is a green one that they had been using, but the unloaders were leaking air and they didn’t know how to fix. The other one had to have been sitting in some industrial plant as a spare. It looks to have never run, but the bearings have some play in them. Guy said it knocked when he tried it out. My guess is maybe it got started up without any oil. I paid 220 for the 2 compressors, one tank, and one 6 months-1 year old electric 5hp motor. All three look like they can be rebuilt without a problem. The biggest problem on the 2 stage is the wrist pin on the little high pressure piston. Both of my 310’s needed new wrist pins and bushings. I think that is pretty common on well used compressors. Oil was probably not changed enough. Both 310’s were pre pressure oil units. The one I currently use was built around 49’ or 50’ and was taken out of service around 01-02’ due to a rod knock.
My point in telling you all of this is that deals are out there. Don’t pay to much for one that you don’t know the condition of. Even completely rebuilt, it blows my mind someone is asking 3400 for that one in Dallas. Depends on what you can find, but you should be able to rebuild one including core for under 1000 as long as no major machine work is needed.