The 1st MP3 player I received from my parents ran off a single AAA battery and could store an hour of music at 128 kbps per file (big waste of money on their part and I also didn't ask for it either).
Yeah, I can imagine and totally get what you mean. like even in the earlier days of that stuff it would have been bad because only 1hr of music @ 128kbps is a joke as it's less than a standard AUDIO CD and for the cost one would be better off using portable CD player at that point overall.
I had a RCA Lyra (don't remember exact model) MP3 player years ago and while it was nice in the sense it ran on a single AA battery, storage space was a bit weak but at least it was better than only 1 hour as at least I could store some music on it but even then it was limited. I want to say I either had a 256MB or 512MB SD card in it (I don't remember the max on that but my guess is probably 512MB or 1GB), which was usable, but still a bit weak for storage space.
that's one thing I like about AGPTEK-U3(8GB) I got last month (for $25) is it runs on a single AAA battery (I use a 800mAh NiMh battery which is actually 800mAh according to my Powerex C9000) and seems to last around 12 hours (probably at least 10 hours or so as the device officially claims 'up to 10 hours'), which I always like NiMh AA/AAA tech over rechargeable lithium since it will always be easy enough to find quality batteries for the foreseeable future unlike rechargeable lithium batteries which eventually will be hard to come by for a random device and then the device is pretty much junk because of that. NOTE: I am not the type of person who always upgrades tech as if something works well enough I plan on using it for the foreseeable future.
with that said, while that AGPTEK-U3 MP3 player works fine so far, I do wonder about it's longevity since it's cheap china made, so quality might be suspect. but who knows, maybe it will last many years or it could be dead in the not too distant future. but that AGPTEK-U3(8GB) (of which I am currently using a 16GB MicroSD card in it (the device claims it can use up to 128GB MicroSD card)) is like those older MP3 players from the 2000's except it's got plenty of storage space which was the primary flaw of those older/good brand name players of the 2000's that used regular batteries. hopefully it lasts at least 3-5 years, but on the bright side at least I only paid $25 for it so I took a chance on it as, assume it stays working, it was a good buy for the price and ill never have to worry about lack of storage space or lack of quality batteries for it.
but it's a shame you can't find quality/name brand MP3 players that run on regular AA/AAA batteries though as while one could always opt for AAA/AA powered MP3 players from quite a few years ago, the problem with those is lack of storage space as I would imagine many of those were probably 512MB to 1GB of storage space at most and I am of the mindset I would want at least 4-8GB of storage at minimum since any less than that is too limiting for anyone with a decent sized music collection and don't want to be swapping music in-and-out of it here and there.