Yup, beyond 30 days. Actually not sure if I have the TEP, but I don't think so. I'll try dealing with a radioschack near here, they might cut me some slack. I'll also purchase TEP and a case.
Honestly, I'll do whatever it takes to get my phone to not look like this anymore.
Normally, Sprint only allows you to enroll in TEP within 30 days of the purchase of your phone. However, to celebrate their pricing increase of TEP from $7/month to $8/month, for the month of August only, they are letting any customer enroll in TEP regardless of how long ago they purchased their phone. While I do not advocate going this route, you could enroll, file a claim, pay the $100 deductible, and get a new or refurbsihed Evo 3D.
Alternatively, if its just the battery cover that is roughed up, you can purchase a replacement cover on ebay for $25 or so. I wouldn't count on much help from RadioShack though, they have no incentive to replace your phone for anything less than the full unsubsidized price of the phone. Anything less and they would be taking a loss. A corporate Sprint store is your best bet but I can tell you right now that if the phone is working fine and its just cosmetic damage, their policy is not to offer a replacement.
For a case, I would recommend getting one from tpu-cases.com. Very inexpensive but fits the phone like a glove and to me, it offers the best compromise between protection and not adding too much bulk to the phone.