They do, check Radio Shack. They actually have a website too. Be warned, though, because these antennas are junk for CB use.
Do your self a favor and get a real antenna for your CB. A 9 foot whip is the best. If you don't like the look, go for a mag mount Wilson or a K40. I prefer the Wilson, and it is more durable than the K40. Try to avoid the firestik, mount to the bumper...
If you are "entry level" and just want something to talk with your buddies a little ways up the road, Uniden 510XL is small and works ok. I have seen them as cheap as $40 at places like Kmart. A lot of my 4wd buddies have them, and they work ok. It is best to put the $$$ into the antenna.
I have use a Uniden Grant XL (same as the Cobra 148) which has a lot more bells and whistles, and of course works a lot better than the 510. Namely, it cuts out a lot of engine static, and has a better recieve and transmit quality. It also has sinde band capability, which is something different than standard AM tranmission. The Grant XL goes for about $135 on-line mail order.
Basically, if you get any name-brand cb you should be ok. More money gets you more features which improve your communication ability. Send me a private message if any other questions, I don't visit this page often.
Also important for your cb, is to get the radio tweaked and peaked, and the antenna matched. Tweak and peak adjust the radio to put out max power, tweak is to set to the proper frequenices. Cobra is notorious for having their radios de-tuned in the power output to cut down on warranty repairs. My friend had his at 3/4 of a watt from the factory. I took it to the local cb shop and they got it up to 7-8 watts. A big difference.
just a word of caution on the 9ft whip antenna: many trails and clubs prohibit the use of a whip to prevent injuries to volunteer/club trail spotters, as these antennas do just that (whip) when trucks bounce around on rocky trails. Also, clearance on tight trails with overhanging trees can be a problem (make sure you use a spring base mount). I have a 102" whip on my Bronco, and even on the beaches there can be a problem with the surrounding public! Be careful.