Hi Amigajoe,
I haven't tried the list of wholsales from eBay, but I know from past experience that I have sourced a number of MP4 manufacturers from the internet and have used them. They are CHEAPER than what you get on retail or eBay but it depends on WHO you get from them. Some classify themselves as "manufacturers" but they are only middle man while some others actually overprice their players anyway because you are from a Western country.
I've found the best source of manufacturers is from:
http://www.globalsources.com/.
However, you really need to asking a lot of manufacturers to get the best price. The first price they give you is generally not the cheapest and you have to sometimes haggle it down.
Sample quantities are generally ok to ask for but they do charge more for them.
Hope that information helps.