Ouch!
EDIT: This was a question in the photography thread, so I replied to Mr Fresh that I'd answer here!
Budget is a first consideration, secondly is what she likes to photograph. Is she using the iPhone because it's small and she's always got it on her, or because that's all she's got? If the former than something compact would be good. If she's really into photography then something a bit larger could work.
She uses her iPhone because that's all she has. My budget probably would be in the $200-$400 range. Well she just started getting into taking pictures of the city and nature but she always enjoyed taking pictures of people.