Besides the fact that you are abusing the terms of your Amazon Prime agreement (breaking the contract, which is a legal offense), have you thought about how much you have to mark up the price to cover your costs?
If you buy something on Amazon for $100 and sell it for $125 on eBay you will NOT cover all your costs. You won't be making any money. It's not just the eBay fees and PayPal fees, you also have to pay listing fees for all the items that didn't sell the first time, second time or third or fourth or fifth time you listed them, plus monthly store fees, plus the cost of handling returns, plus taxes, plus your time.
I remember one re-seller who was drop-shipping was in shock when he added up the numbers at the end of the year and discovered he had LOST a few thousand dollars. If you consider that you have to manage your eBay account seven days a week, that's a huge loss of time, as well.
Also consider that if you are charging, let's say $135 for an item that sells on Amazon for $100 why would the buyer buy it? Probably both Amazon and eBay buyers will buy from a different seller to get it cheaper. You can't buy at retail prices and resell at retail prices. You have to buy wholesale (below-wholesale, actually) if you want to make money.
Also, it probably won't last very long. Some buyers will report you to Amazon if they see you are abusing your Prime privileges.
