I have a DB32 antenna from my old Optoelectronics Scout frequency counter. It is almost identical to the Comet CH-32 antenna mentioned above. I have it attached to my 246T right now and it's hearing our statewide 800 MHz system just fine. I also have the Radio Shack 800 MHz antenna which is even better but this antenna really does seem fine for all practical use. In fact, I had the same idea as you -- try to get the smallest radio possible without losing reception. And it works great. Carried it thru walmart the other day on my belt w/ the tiny antenna and was hearing UHF crystal clear as well. The DB32 is $49 on the Optoelectronics website and the CH-32 is only $27 at Universal Radio, so I'd go w/ the CH-32. This should work out very well for you and even if you find it doesn't, I doubt you'd have too much trouble selling it off to someone else for at least $20.
After walking around a bit, I realized I should also add that it makes a difference what kind of environment you are going to use it in. If I am trying to walk around the building I'm in, it's in and out. But that's probably because the system only has two tower sites that are each a good distance away. The city's multi-site EDACS system has something like 9-10 tower sites and I can hear that one just about anywhere with almost no antenna. But keep the tower signal strength factor in mind.