Peter, the bedroll does the job really well, is light to pack, can double as bedding if you are camping, and at $12.95 from K-Mart, it makes far more financial sense that a $250 Meade dew shield......what are you image-conscious, or something??!!
The dew zapper does a great job, but it sucks the power from my battery pack, so I have found it works best to use the bedroll most of the time, and only employ the dew zapper, care of a second battery pack, if the dew is particularly heavy. I also carry a hair dryer, which does a great job when the corrector plate or eyepieces fog up. You might look at that as well in preference to an expensive dew shield.