This question about "decent" quality Portable DTVs has been asked on several of the AV/Home Theatre forums and I know for a fact it's been kicked around inside the industry. Samsung and a few others have just released and/or are releasing smaller (and cheaper) chip sets so more products will appear. In the meantime I believe there are two choices....

1) A low quality unit like Insignia or other things out of China. Here are two with battery pack and charger options:
7" and 8" Portable DTVs


2) Think differently and step "around" the issues of hungry ATSC chips sets, cliff-effect reception, low quality manufacturers. Check this out:
Truly Portable DirecTV

This thing is self-contained with antenae, battery pack and 17" screen. Yes you must subscribe and it's expesive, but maybe the coolest solution out there!

Hope this helps,