There's always better, cheaper options than Straight Talk, and selecting them over Straight Talk allows you to pretty well select nearly any device you want from that point instead of being restricted to the devices they offer. The secret is to determine what network she's on to know who to jump to.
If the current phone has a SIM card in it (usually in the battery compartment), check for the markings C4 or T5 on it. If it's C4, she's on the AT&T network. If it's T5, she's on T-Mobile. If there is no SIM card, it's a CDMA phone, which means she's on Verizon.
Airvoice = AT&T
P'tel & Spot Mobile = T-Mobile
Page Plus = Verizon
Any carrier unlocked GSM 850/1900 phone with clean IMEI will work with either Airvoice or P'tel. Any non 4G LTE Verizon handset with a clean ESN will activate on Page Plus (excluding iPhone, Blackberry and Verizon Prepaid). Of the two technologies (GSM and CDMA), you're going to have a far nicer selection of phones available on the GSM end due to the restrictions on the Verizon end.
If she's wanting a "cameraphone", she's probably going to want something that has a bit of resolution to it. All cameras on phones stink out loud at worst and are only as good as an instamatic at best. Your better cameras are going to be on smartphones over feature phones, however. Once you have a rough idea of what you're looking for, hit up the following search tools to find some good candidates.
http://www.gsmarena.com/search.php3http://www.phonescoop.com/phones/finder.phpThe first couple posts on the Superguide should carry you the rest of the way:
https://forum.mrmoneymustache.com/share-your-badassity/communications-tech-isps-voip-cell/