Katelyn, in my opinion there is nothing more suitable for your needs than the 505 with the light wedge. Ebook formats can be very easily converted with the great and free
Calibre.
My choice is the PRS-600 and
Verilux Natural Spectrum Reading Light. Whereas I am going to buy the 600 next week, I have been using the Verilux Natural Spectrum Reading Light for about a year and I love it. I use it quite often despite the fact that I also own the PRS-505 light wedge.
BTW, how long has it taken for your 505 to get to the stage of flaking out?