I've had numerous tablets and android phones starting with the very first G1 phone. Also dabbled in android development a bit.
The economy tablets that you generally see out there tend to be pretty cheap and skim on materials. Generally the hardware and software implementation on them are pretty cheap and their android implementation is pretty buggy. They also are not licensed by google so there is no google apps such as the android market, gmail, youtube, gtalk etc.
I would recommend a tablet such as these
only to those that can reflash the firmware on the units and only if there is a nice variety of firmware out there developed by third party developers. A good friend of mine owns and operates
http://www.slatedroid.com , an android tablet forum. If you happen to find a tablet that you may be interested in, cross reference it with some of the posts on their forums. Chances are, there is someone there that has already posted their experiences with it and there may also be some firmware there for your model tablet.