Unless you seriously can't think of anything else to do with a working handset that you're not using, then the fact that Radio Shack will take it and give you a $100 instant-rebate on the HTC EVO in return isn't that big of a deal.
I mean, yes, a $99 EVO is great (old) news. But it's not as good as other sites are making it sound.
Radio Shack has been selling black EVOs for $99 online for at least a month already, remember? Amazon Wireless has been doing it off-and-on for the past two months, and Walmart Wireless did it too (that one was $49.99 for new contracts and $99.99 for renewals). And no one had to give anyone else a phone that could be sold on eBay or Craiglist either.
In other words, you don't have to give away another phone to get an EVO for $99.
If you insist, however, then the Radio Shack "deal" comes with a free Bluetooth headset (which is probably worth less than you could sell your other phone for) and is going on until Christmas.[SprintUsers] Thanks, MsRandall!