For cheapscates like me, there is the “bring your own phone” at Tracfone. You can buy a used Verizon Iphone 4 or 4S on Ebay and activate it as a Tracfone. Be sure it is not Icloud locked and has clean ESN
Word of caution about iPhones on Tracfone networks.
You may have a good deal of difficulty getting them to connect to cellular data, and the photo send and receive feature may not work at all.
All Verizon Iphones (5 and below) are sim-unlocked.
That means you can put a compatible sim card in it and it will work for Trac or Straight Talk (which are the same company) on the GSM network (aka ATT or T-Mobile).
You can use a Verizon Iphone 5 on the CDMA network (a.k.a Verizon’s network) under Straight Talk (ST), but you’ll be limited to 3G speeds for data.