Tmobile Mytouch 4g portable charger?

[Damion]

Ok well my mom and I are getting the Tmobile Mytouch 4g phones within the next couple of days. I was reading reviews on the phones and the battery seems to be it's only real issue. Im looking for either a portable charger or a pack that holds a second battery and charges it. I know there are plenty of chargers / packs out there I have never needed one though and I don't know much about them. Any tips or info on what to get and where to get it would be great. Price isn't a big deal but if cheaper works just as well as a more expensive one then cheap is good, like I said I have never used any so I just don't know. Thanks for any help or info you can provide