If we assume a $5 price, and a standard US contract rate of ~$100hr (cheap for US contracting actually) and we ignore the cut taken by credit card companies and such (ha!), then we're talking 20 sales to pay for 1hr of development. I don't think they made this plus the site with < 20 hrs and I assume they'll be spending at least 1hr doing email support so 400 sales just to cover their time making it. Or 420 sales to break even... for an extremely niche product.
Still think $29 is too expensive?