Looking at the Kobo devices, you can get the 6" Clara HD, the 6.8" Kobo H2O v2 and the 8" Forma. I've owned several Kobo ereaders and they've worked well for me. The 7.8" Aura One is still my main ereader since shortly after I purchased the Forma, it was "borrowed" by my wife who is still very happy with it.
I'm not certain what the prices are in the USA (I'm assuming anyone who is using a Nook is living there) but Walmart does have their Kobo ereader selection at
Kobo eReaders. Walmart's stock seems to be very hit and miss. Ghod alone knows why it's easier to search Walmart using Google instead of Walmart's own search. There is also Kobo's own site but Walmart allows in-store pickup which beats having someone leave your new ereader sitting on your front porch.
If you are interested in the weight:
Clara HD 173 grams
H2O v2 207 grams
Forma 197 grams
One item to note is that the Kobo ereaders are eInk devices so 16 shades of grey. My Clara HD allows me about 25 hours of reading before I start worrying about the battery needing charging.