I have a CB in the truck it comes in handy.
You don't need anything too extreme.
A basic cobra 19 40 channel 3 buttons power/volume, squelch and channel 50 - 75 bucks works fine Ive had one in my truck for over 6 years. It recently stopped working. Not bad for being shook around for six plus years. Not sure if its the wiring, CB itself, or just a good excuse to install the 29LTD my brother bought me for my BD back in August.
If you want more bells and whistles a Cobra 29 LTD 100 - 150 bucks Fancier and nicer especially, if you run duals or want to be able to fine tune it on the fly. Its still basic enough so you don't need an engineering degree to install and use it.
R.F. communications secretes.
1) What kind of vehicle are you running?
C van you can get away with a single 36 or 48 inch antenna and will have better performance with a single on a van. If you want the dual look have one wired and working and the other as a dummy or posably for the AM/FM radio. There are adapters to tie them together but make sure you check the owners manual for your vehicle radio so you don't have problems. Keep in mind if its not broke don't fix it.
Trucks singles get the job done but you can get better reception and broadcast with duals. That's because they have a box or trailer and this scatters the signal.
2) Most CBs come adjusted to apx 80% of their wattage output.
Pay the extra bucks and have it peaked and tuned? Its worth it if you plan on, or wind up using the radio allot, or realize you want better reception. A good shop will tell you if its worth the extra dough and what they can do. A basic peak and tune 20 or 30 bucks, the price goes up from there for more advanced work like swapping chips etc. As a piece of advice if they don't want to at least let you watch and tell you " its a trade secrete" find someone else. They will likely take it into the back room and screw off for five or ten minutes, and hand you back an unchanged radio.
The most important factor is the antenna cable and the antenna itself.
Fiberglass Antennas are inexpensive, durable, and come as kits to get you started. Again I've been running mine for the past six plus years in the north east with a Cobra 19 sound check, 36 inch fiberglass truck stop antenna kit, and can skip 2 or 3 miles legal wattage.
If you can keep it legal try to get antennas that will clear the box by at least 6 to 12 inches. More is better but remember the 13'6" height clearance, and mount them as far apart as possible and a slight tip aprox. 20 deg forward of the box to reduce scattering the signal across the box.
Tips with the coax. 1 you don't need 18 feet of cable for a 1/2 wave it does help to keep it in increments of 9 feet. 9 feet will achieve a 1/4 length and will work fine. 2 Don't coil it in the headliner try to lay it flat as possible so you don't create a choker. If you have extra lay it in a smooth serpentine pattern.
Make sure the ends are soldered onto the coax. Cheaper junk coax is crimped they will fail you.
Tunable like Firestix are better but are more expensive and better suited for dual setups. A good cable I'm running with Beldin or Roadpro 8x clear jacket coax with good results I'm planning on upgrading the antennas when I install the new radio after a P&T and should be able to skip 5 miles legal.
But as a starter and for the money an antenna kit at a truck stop will do just fine.
Besides, If you realize you don't like the CB or simply drive with it off 90% of the time you wont break the bank.
Last but not least keep the wattage legal the FCC doesn't bother as much with wattage now days as they did 15, 20 years ago when CBs were more popular but they do check on occasion.
Good luck and PM me if I can help.
Bob Wolf.