Saw these on eBay, I tried one out and they work pretty good. It doubled the reception on the RS PRO 106 scanner. It's a magnetic base so it sticks to anything metal and harnesses the metal object as an antenna.
eBay: http://pages.ebay.com/link/?nav=item.view&id=161245384693
eBay: http://pages.ebay.com/link/?nav=item.view&id=161245384693