The simplest gear is often the most effective. For the past few months I've been doing my handgun accuracy tests off MTM Case-Gard's pistol rest ($20). It's a molded-plastic platform with a broad, adjustable plastic fork covered in rubber. The fork can accommodate about any handgun you could think of, and it can be adjusted to 20 different heights. Moving the fork up and down requires squeezing it and pulling it back—disengaging its "teeth" from those in the platform—and then re-engaging it. It does take a bit of experience before you get the hang of doing it, but once you do, adjustments are easy.
You may notice the rest in the photo above looks a little different from the product image you'll see at mtmcase-gard.com. That's because mine is an older version. It had a plain plastic platform, and I didn't like the slick surface, so I slapped some semi-tacky shelf liner on the platform with contact cement. The current version features a soft, rubbery foam pad to accomplish the same thing I did—saving you a trip to the hardware store.
The rest works great for ammunition testing, and what I really like about it is it's light and compact—and indestructible. I just toss it in the back of my car and off I go. I usually leave it set up, but if you need to store it in a tight space, detach the the fork unit and snap it into the underside of the platform itself.