Suggestions Welcome

Here's my current quandry:

I received $200 worth of Borders gift cards for Christmas.  Most of the books I want to buy (and there are many) I can get cheaper on Amazon - frequently by buying used books through some other retailer that Amazon, puzzlingly, tells me about..  It chafes to spend more money, even though it's gift money, on a book when I could get the book for less (if I use the Borders website and try to buy used books through them, I can't use the Borders card). 

Now, it just so happens that Borders also sells, in addition to books, a Sony e-reader that has gotten good reviews and if someone had just given me this for Christmas, I'd have been very happy.  But, the choice to purchase it is just laden with land-mines (fyi - choice is not a good thing...the toothpaste aisle in the grocery store sucks up an unreasonable amount of my time as I try to figure out which choice is the right one). 

(1) Would reading pdfs (that'd be the primary reason to get an e-reader) on a tablet be a good idea?  All the reviews say that reading on e-readers is less taxing on eyes than reading on a regular computer screen and all tablets that are out now are not of the e-reader variety

(2) Should I get the Apple ipad (silly name notwithstanding)

(3) Then the ever present, should I wait until the next tablet, e-reader comes out

Now, if I don't get this e-reader from Borders and, instead, get either a tablet or get nothing, I still have the Borders gift cards to contend with and the spending more (of someone else's) money than I would of my own money.