Just request a 2 week holter fom the doctor.. Cant vouch for buying one.. Because as tom said who will read it?
Further you need a physician to verify the results and actually treat it. If you put it on yourself you're likely to have difficulty getting your insurance to cover treatment regardless of what you find.
The first question I'd ask you is , What is he feeling?
Some arrhythmia can be monitored with a simple 2 or 3 lead recorder. Yeah, if you get a 24hr. hospital Holter, you'll probably get the kind with the full compliment of leads. But is it necessary to see all the angles when you're just looking for evidence of what he says he's experiencing? 7 years ago, I wore a 3 memory, loop recorder for 1 solid month. The recorder would send any recordings which were triggered by a number of set point criteria. I wore it only to confirm what I said I was experiencing, and it was absolutely key to my being successfully treated. It was a simple 2 lead device, one on my the side on the rib cage, and one up above my nipple. That's all it took. I got 3 good recordings, and thats all they needed. Now, if you're dead set on getting your own, consider how you're going to get someone to read them quickly. This is usually a "package deal" with the recorder and analysis rolled into one.
One other thing. Those pads begin to hurt like heck after a few days of wearing them. The saline electrolyte annoyed my skin to the point of it breaking out in red welts. It was bad enough moving around 2 leads for 30 days to allow one area a day of rest. Think about this and think about the alternatives. Also, please describe what he's feeling.