Seeing as your wife has had a lumia 520, have you considered a Lumia 550?  

Our son smashed her 530 so had to look for a replacement, luckily for us the warehouse were selling the 550 for $79 at the time (carrier locked to Voda tho) so we picked that up.  

Have to say I'm pretty impressed with it, compared with the 530 and even my own 920!  For the price it's not a bad device at all.