There are PATA SSDs out there if you look for 'em, might find some on eBay (I had to get one a long time ago). Some of them will have a 1.8" size and require an adapter to make it compatible with the 2.5" connector.
I think I have a Hitachi 60GB 2.5" IDE around here someplace if you're interested, had no issues the last time I checked it out but I have to look for it, might have tossed it at some point so I'll PM you if I'm able to find it.
I have a 2.5" PATA 160GB Seagate from years ago that I got when I RMA'd a 120GB. Would you be able to format that down to what you need? The last several years, it has just been sitting in a 2.5" external enclosure that I rarely power on. I have no idea what is even on it. I'd have to take whatever off of it and wipe it. It'd easily fit in the smallest flat rate shipping box, whatever that costs these days is really all I'd ask. Honestly, it'd be doing me a favor making me get whatever is on it off of it so I can get rid of a mostly-worthless computer part, lol
Just noticed you said you were going to use this in an enclosure.. you can pick up a SATA enclosure for the same price as shipping any of these drives to you, and then you could spend a little more and get a cheap SSD. MUCH faster for seeking through your music, and as mentioned above, arguably more reliable with vibrations and such.
My reason for reusing the PATA enclosure is that I know it plays nicely with my car. I've already tried a number of flash drives with mixed success. I don't want to buy an enclosure and SSD only to run into the same problems I've had with the flash drives.