Blink's absolutely right, there is zero correlation between your ability and the price your work goes for on ebay.
I think the starting bid isn't bad (some people start at over $50 and they never sell) but I know that some builders have success because they start their bids really, really low around $5 but have a much higher reserve price. The conventional ebay logic is that way you get a higher volume of bids which eventually drives the price up higher.
I think if you want to see an example of someone who uses ebay really effectively check out
Puppet Planet. Michelle uses ebay to build awareness of her work, but doesn't use it as her primary sales channel. Most people can't get good prices for their puppets on ebay, but the auctions often lead to other, full-price sales and commissions for custom work.