Here's my list going back to 2009, all were purchased new unless otherwise noted. I too have a problem. I think if I could get a device with the Paperwhite 2's lit screen and Sony's collections capabilities I could be happy. Of course it needs to come in a 6 or 7 inch as well as a 10-12 inch for PDF's.
Sony
PRS 505 – 5 total (2 purchased new, 3 purchased used, 1 gifted, 1 dead)
PRS 600 – 1 (sold)
PRS 650 – 2 (1 died, 1 used replacement for dead one)
PRS300
PRS350
T1 – 3 ( always good to have a spare or 2)
Astak
Pocket Pro
Pandigital
Novel 7
Apple
Ipad 1
Ipad Mini with Retina Display
Ipad Air (on order)
Nook
SimpleTouch with Glowlight – 2 (that needing a spare thing again)
Glow – going back to the store, will not connect with home wifi
Amazon
Kindle 2 – sold
Kindle Touch – 2 (1 new and 1 refurbished)
Kindle PW 1 – traded in
Kindle DX
Kindle PW2 – current main device
Kindle Fire HD7
Kindle Fire HDX7 – returned
Kindle Fire HDX 8.9
Kobo
Glo
Aura HD
Nexus
Galaxy S3 Tab 10.1
Asus
MeMO Pad HD 7 inch
MeMo Pad FHD 10
The Ipad Air and both 10 inch tablets are still within the return window. 1 of these has to go back to the store!