So far, i have collected:

Palm Vx (bought for spares, but only need a charge)

Palm M105 (a bit bulky, but only needs standard batteries)

Palm M515 (replaced the battery with a new one)

palm T/E (got this one new, but hardly used it as... it never hold the charge for long)

And a Psion 5 series this is a far better alternative to the Palm units, with a bigger screen, touch screen and full keyboard