Mate, for those extremely low prices ($35 -$50) I wouldn't be worried about advanced features!
It all depends, (as in everything), what you want to USE it for!! If it has 2-gb & a slot for a micro
card add-on, (can download what ever apps you like, (sort of!)), has a half reasonable camera,
(no professional shots!), can make phone-calls, Text, & MMS, what more do you want?!!
Obviously you do not want it 'locked' into a particular 'provider'!! Review each 'option' yourself.
But at that price, most of us wouldn't even worry about quality, if we just wanted a cheap device
as an emergency backup. It's like having to drive to the shops. You don't need a Lamborghini to do
that!! The 'latest' 'smart-phones' from $600-$1400 are NOT needed for those that want/need basics!