Keep in mind that the time will come where prices will drop with new versions possibly coming out and you may also have extra returns because of that.
A seller is selling the iPad Air 2 64GB
The gold version is selling on Amazon for between $545-$550. The other versions are similarly priced. FBA fees are ~$35 at a sale of $550 (Shipping is separate but should be $5 or less - try to ship as many items as possible in one package).
You would earn about $10-$15 on the sale. A good start.
So here's the magic:
Start with Top Cashback and earn 1.2% - $6.
8% in eBay Bucks - Targeted - $40
Use up eBay Gift Cards - Seriously, though, you can either use eBay gift cards which hopefully you bought at a discount or you can use a credit card that earns 2% which would be another ~$10.
Alternatively, you could buy eBay Gift Cards on Raise for 2% off and still get your 2% from your credit card. You can also buy from Gift Card Mart for up to 2.9%, but they are small denominations ($25-$50). That would add an extra $10-$15
Both Raise and Gift Card Mart allow you to use American Express Gift Cards which can add an extra 2% of savings if you bought them with a Fidelity American Express card when Top Cashback was paying 2.25 for AGCs. That would an extra $10
Overall, you could conservatively earn about $75 per iPad you buy and resell, close to 15%, with potential for more if you have American Express Gift Cards to use or discounted eBay Gift Cards from other sales. Not too shabby!
You could also use ShopatHome for 2%. I've never used them for eBay and some have expressed issues with tracking on eBay. I have had no issues with TCB and eBay. Please comment below if you ever have used ShopatHome for eBay and what your experience has been. Thanks.