I think the max you can get 90,000 miles as 50,000 miles is the limit on the bonus miles. (I am including the Pointsplus bonus miles in the 50k)
You would need to get 86000ish ebay anypoints to get the 40k miles which then would attracted the 50k in bonus miles (Special 3rd birthday promo on
www.points.com).
Also should you not be the buyer at the auction as he/she is the one who receives the ebay points for buying the item?
I still quite like the idea of earning 1500 ebaypoints/1600 miles per priceline stay.
The limit on my paypal account is 550GBP (1000US).