i'm guess estimating here @ a $500 ending price.

5.25% of the initial $25.00 ($1.31), plus 3.00% of the remaining closing value balance ($25.01 to $1,000.00)

eBay
1.31 + ($475 * .03) = $15.56

PayPal
$500 * .03 (a 3% paypal fee) = $15

total fees, $30.56


Assuming you got the system in the store and had to pay a resonable tax.

Wii
$249.99 * 1.07 = 267.49

so,
$500 (sell) - 267.49 (cost of goods) - $30.56 (fees) = +$201.95



Tell me a stock you can turn for an 80% profit within hours.