I just reporting this as an incredible (to me) fact.

I was asking a seller about a 14 lb. LaneMasters World Class Reactive. He had it listed for $150 + $30 shipping. He said he paid $169 for it. That's quite possible. I told him it was worth no more than $130 shipped to me. That's when he told me that
Ebay would charge him $15.80 in fees for the sale of this ball.

I was in shock, to say the least. I wished him good luck. (and extended my sympathies.)

10% on fees through ebay includding shipping fees. Another 3-6% on paypal fees.

If you look up what EBAY's worth is, you would never want to use their services again.  Than look up what past and present Owners and CEO's of EBAY have made per year. 

EBAY makes astronomical amounts of money off you, but they are the biggest and most widely know auction site in the world.  You pay for the number of eyes that see and bid on your auction.

EBAY is a buy low, resale high game not a buy high and try to re-coup your money or make a profit game.

With bowling balls it's pretty much a loss unless you have something rare or bought a ball relatively cheap and can make a profit.   You have to be happy with making $15 to $20 in profit on your good sales.   
   

Some things I've learned.  Storm and Roto Grip balls get the most looks.   Some of the off brands get good looks like (Lane Masters, Visionary, Lane #1 etc).  If it's 16lbs you better take what you can for it.  Auctions need to end on a Wed or Thursday at around 8 to 9pm your local time.   

Your better off rolling the dice if you want bids and don't put reserves or high starting prices, people seem to like to play the bidding game instead of just paying the market price right away.  (You can get 20 bids on an item and sell it for $50, but if you list it for $50 nobody bids,  unless you offer free shipping.  People seem to over bid with free shipping). 

Bowling ball prices are all over the place.  One week you can sell a ball for $80 the next week the same ball gets $20.   This doesn't not help the seller in trusting the market and taking a hit on profit.  Then the whole people don't want to bid if there is a reserve price comes into play. 

10% is a little harsh to get hit for on higher prices stuff, maybe let its better to let the auction expire and sell it privately after. How much is fee if its not sold and expires?

It's already a hassle to deal with deadbeat buyers via eBay and Paypal, who really wants to risk what you're suggesting?