It's not even close to $10 profit if you sell a book for $50 on ebay.
$16.2 Cgc fee(10%): not all of us have the dealer discount of 20%
$5 handling fee
$10 return shipping: for 1 book. You need to submit 50+ book to get avg of $3/book.
$3+ shipping cost to cgc, media/first class mail
$6.25 ebay & papal fee
$3 book cost
$43.45 for 1 book cost that not fast track.
I rather sell it raw for the less hassle. Only worth the time if Cgc book sell for $70+. $7 profit for 3 months waiting and your money tie up ($43.45 initial cost), not worth at all. This also has not included the fee that ebay & paypal charge you for the shipping you charge the buyer.
This means that you have to submit at least 2 books to worth your time. Assume all book graded 9.8, if any failed then you cut in your profit. This is standard modern submission, anything can happen, price go up or down. Fast track is even worse, -$9/book. For 3 books, you make $24 profit. Selling raw, you make over $15 profit for 3 books.