The Jornadas are older models so they'd all be secondhand I would think. No particular vendor that I know of, I just know they were generally cheaper than other PDAs running Windows Mobile from Australian ebay sellers (where I am) at least, and I was looking to get one until a particularly cheap Ipaq turned up.
Good chance that the secondhand PDAs running rechargeable batteries will require new ones but they are cheap and easily found on ebay too