Deal # 2 - Book Flip on eBay with ROI of 170%

This deal explains how I flipped a book on eBay with a return on investment of 170%. I bought the book from a local thrift store and sold it on eBay for profit.
What I Flipped: This cool finance book. It was in overall good shape and only had writing on a few pages. I looked on eBay and saw that some sales had been completed in the past couple of months for around $10. I skimmed through it and it actually has some good points, the main one being don't undervalue what your time is worth.
Where I Bought it From: A local thrift store
Where I Sold It: eBay
Finer Finance Details:
Cost of Item: $1.00
Sell Price: $6.50
Net Profit : $6.50 - $0.65 (ebay) - $0.49 (Paypal) - $2.66 (shipping) - $1.00 (cost) = $1.70
ROI = (Net Profit / Cost) x 100 = 170%
Money Currently in the Flipping Pot: $2.70
What I Learned from this Flip:
1) You have to be patient when it comes to flipping things. I had to wait over a month for this to sell. Related to this point, I need to find books in higher demand which will sell quicker.
2) Don't give in to low-ball offers! If I had given in to a $5 offer then I would have made almost nothing from this flip.
3) Only click on the Print Postage Label once on eBay. I hit it twice and they charged me twice for postage but I'm just waiting on a refund for one of them.
4) Paypal charges 2.9% + $0.30 for each transaction! And eBay charges 10% of final value. If I'm not careful those fees are gonna kill me. It's best to calculate those beforehand so you know what price point you need to sell the book at.
5) Lastly, I learned that books are cheaper to mail because you can use media mail from USPS.
In the end, I am stoked that I was able to get $2.70 back from this book flip deal! Trying to find something to flip for $1 isn't easy, but it's definitely doable. This deal was way more successful than Deal #1, where I lost 2 cents overall.
It will be much easier I think to find a book for $2 or $2.50 now that there is $2.70 in the flipping pot :)
Wish me luck!