In a nutshell: this is perfect if you don't need to navigate folders or see track titles.
Fingers crossed, I've found my ideal daily-use player. They can still be a little expensive for what they are (the new-in-box MP3256D10 was £6.69 inc. p&p, though I later got a used MP31GD10 1Gb version for £3.79 and MP3128D6 for £2.93) — however, unlike many other budget players that allow you to use AAA batteries and memory cards, Alba came up with something that just works and does the range of things it does well. This means I can retire my SnowFox player that gets upset by knocks (but does do folder navigation and track titles) to use as a bedtime audiobook player.
The key feature for me is an easily-selected random play mode that genuinely does play tracks randomly and doesn't fit itself to a pattern... which unfortunately isn't as common as you'd think in the lower end MP3 player market.
Claimed battery life is about eight hours; expect this to be less with cheap batteries or when playing non-MP3 files. When there are files on both the memory and a card, the player treats the two sources as separately numbered lists, but there doesn't appear to be a way to quickly skip between sources. Settings are stored in a SETTINGS.DAT file on the internal memory that gets recreated automatically if deleted, and apparently the player can handle non-DRM WMA files as well as the MP3 format.
I habitually rip CDs using "--preset fast standard" (which averages out to about 192kbps) but re-encode to mono VBR with a max bitrate of 128kbps for things that'll be used on MP3 players. This gives about 300 tracks on a 1Gb card, or 20 albums. Generally I'll have one card with tracks I like to play on shuffle and other cards with selections of albums I like all of the tracks on, with the albums on the latter having the tracks joined together so there's one MP3 for the entire album. This does me for times I'm waiting around or travelling, and is the reason I don't just get a flash player with a large capacity and/or with a built-in rechargeable battery — besides which, I prefer my ordinary carry tech to be of disposable value.
Alba also did a similar size silver player (MP3128D6 or MP3128D6SIL) with 128Mb and an SD slot — which may explain why no MP3128D10 code turns up in Google at the moment — and I've also acquired one of these, hence this review being for both types. Its features and operation are the same, even if the button positions are a little different.
The manual specifies a maximum card capacity of 1Gb, but I've tested the players of this type I've bought with a 2Gb card plus over a gig of MP3s and they see all of the tracks. As far as stretching the functionality further goes, there probably is a limit of 999 tracks due to the three-digit display, and it's conceivably possible that 4Gb cards manufactured as SD rather than SDHC might work — but I wouldn't hold your breath on that. With 2Gb cards currently being ~ three quid, these are versatile enough for me.
Possible downsides are: it takes a good few seconds to switch on, SD cards stick out a little rather than sitting flush with the slot, transfer is at USB 1.1 speeds, and the player doesn't store your position within the current track (very few players actually seem to, but once you've owned one that does you kind of get used to it.) The time display gets confused by some very long variable bitrate files (i.e. whole albums as one track) and usually won't display correct times if you try to fast-forward or rewind them, but this appears to be just a display issue that doesn't cause problems with playback.
Looking around, as well as the blue 256Mb and black 1Gb models, white 64Mb and 512Mb ones seem to exist. (The 'D' seems to stand for display, incidentally, as MP3128ND1 and MP364ND5 are for no-display players that don't seem to have an SD slot. MP3512WD3 is a normal stick player. MP3256WDR4 seems to have a screen and radio, but apparently no slot, MP31GDX8 has screen / radio / SD slot (but is unreliable according to reviews) and MP34GD12 is a normal stick player with clip-on covers. MP31GD10BLKXI, somewhat confusingly given the D10 bit, seems to be a normal stick player. On a more random note, I never knew 'Alba' was the Gaelic for 'Scotland'.)
Update: Stax (a wholesaler) are apparently selling the MP31GD10BLKXI now for £7.99 and the photo they provide is of the black 1Gb slot player I've got. So it appears the other site illustrating that code with a normal stick player is mistaken. Wrong product photos on websites are unfortunately very common with MP3 players. I'm also a bit surprised any sizeable stocks of this model still exist, since Alba have a range of newer players in circulation now, but it'll mean more show up on eBay in months to come.