I have had just incredible luck with the old style extendable antennas from Smiley.
http://www.smileyantenna.com/product_info.php?products_id=34I bought a dual band 440/2mm, a 2m and a specifically tuned 443Mhz antenna from them a couple of years ago. They are all great. The dual band collapses to about 5" and works very well on both bands. The 2m is a huge 5/8 wave antenna that can really increase abilities....even though it is quite cumbersome to use. I bought the 443Mhz tuned for our main repeater, but have not found it all that much more efficient than the dual bander.
Inexpensive and impressive. These are setup using interchangable mounts...so you can buy BNC, SMA and a host of other larger mounts....this is great for emergency use as a number of hams will only have their stock rubber duck. You can set them up with a much higher gain antenna if you have a couple of extra mounts.
I have:
Super Stick II for 2m....a 6 to 9dB gain antenna
Super Stick IV for 443...a 6 to 9 db gain antenna
270A Dual Band....excellent for 440 and good for 2m...my most used antenna.
These are around $20 each. Highly recommended.
I have used the thin wire whip dual bands (Pryme) and while they are good they are always in the way and the whipping around seems to cause some reception/transmission noise.