Not like these are cheap, they're priced just slightly under Pentax's K10D grip, something like $199 (with maybe 10-20% discount). Pricey for something so shoddily made and badly crippled. IMHO nothing beats a real vertical grip with proper adjustment dials.
I guess many here like Pentax because their cool little lenses and their compact camera bodies. With a grip on, the K10D will be a quite big camera. I feel the camera already too big w/o the grip. Would have kept a K100D if its SR is as good as the K10D
I have got D-BG1 on my camera. Sometime I like to have it with the grip even when I am using a pancake. Its quite comfortable to hold the camera with the grip on. It also help to balance the weight when using long big lens.
The grip is really good to have... but not a must have.
I have to say that at least something good came out of the last Pentax meetup for me.
I not so gian the vertical grip anymore.
After trying one, I find that it's too awkward for me.
Unless I have a real need for it (can't think of any now), I wouldn't spend the money and time to adjust to it.