Where to get this deal...?

I'm looking to get into the cheapest what I'll call 'wake-up phone' I can get. My regular phone gets calls all the time so when I go to sleep I put it on silent. In case of an emergency I need a second 'wake-up phone' for my close friends and family to call to wake me up. This second phone would never get any talk time put on it as it would only be used to wake me up, at which point I would revert to my regular phone. Actually I had a pre-paid phone like this for a number of years through boost. It only cost me $5 every 90 days to keep it active. That was the minimum amount to keep an account open, and the re-boosts bought online were good for 90 days. Since I forgot and let my service lapse they won't let me get back into it now, said I was grandfathered into that 'plan' since I opened the line a few years ago. Now they say I have to start a $35/mo plan to get back with them.

Anybody know how I can get back into boost or any other similar pre-paid phone deal for as cheap as I used to have?

Or if there's a better place to ask this question please direct.

Thanks