It depends on the price. I bought a whole bunch of accessories for a wheeler and wilson for $1.00. I gave them to Leon. I bought a bunch of unknown bobbins; they were brass, so I knew they had to match something old. I think I paid $1.00 for those as well. I gave those to Skipper. I had a bunch of other strange stuff I didn't need that I sent to Joe for postage. Maybe I'm selfish, but now if I get in trouble with a machine, I can ask Leon, Skipper or Joe. As Steelsewing says, it makes friends when you can share.
The problem I see is identifying what you have. If it didn't come in/with a machine I bought, I don't have a clue what it might fit. I don't have that much experience.
I'll give you an example from another field: I bought a big box of beads at a Goodwill auction. I think I paid $27.00 for them. It's likely there are several hundred dollars worth of beads there. Or, maybe not. They are all some type of stone. I have no clue what kind of stone they are. I thought of selling them on ebay, but what do you say? I have some pretty beads? I looked at online sources to ID them, but couldn't distinguish one pink stone from the other. I've thought about donating them to the local elementary school, but still have all of them, in boxes, in the garage.
I would be that way about sewing machine parts. Now, you can ask here and on Victoriansweatshop.com, and you will likely get an answer or at least some direction. It's a lot of work, but you just might have the perfect part someone really needs. On the other hand, unless you plan on restoring old machines, or have lots of time to research, I'd think twice.
bkay