First of all let me congratulate you on using your E2 for 6+ years. That’s more life than most people get out of their phones.
I hope you are aware that when you get a BYOP phone, those phones work on the My Choice Plan…and not your 2.0 Refund Plan. Another thing to consider is that some of the BYOP phones only work on GSM or T-mobile while you are currently on the CDMA or Sprint coverage. So it would be useful to pick a BYOP that works on either GSM and CDMA, so that you have greater flexibility in terms of coverage. See here for additional info.
Seeing how long you like to use your phones, I don’t think there are any phones in the sub $100 price range that will give you that kind of life going forward. My recommendation to you would be…if you can extend your price range a bit and look in the 150 to 200 range…you will be better served with a newer phone that will last you a while.
Also, as a Refund plan member… I would recommend that you submit a help ticket and explore with RW if they would have any offers for you that might help you with the transition from a 2.0 plan to the My Choice plan.