In the not too distant future, you could get some used iphones - droids off of ebay probably cheaper than a new digi throttle ..
Just an FYI, it doesn't have to be a phone to run
JRMI wifi throtle. While its nice if you have an existing phone that you can repurpose, I'm not sure if it will ever be cost effective to buy a used phone. As long as a device runs the ios or android os with wifi it should work. A refurbished ipod touch from apple is around $160. 7" and smaller android tablets can be found around $100, such as the
Archos 28 for ~$88. Which should put you in/under the price range of current wireless offerings from DCC manufacturers.