Cobra is a good brand, but remember the FCC regulates CB's to 5 watts maximum output. All of the radios (from $20 off ebay to $250 ones) are regulated at this wattage. Many truckers enhance their radios to be more.
The antenna should be simple, and close to a good SWR if the coax is already installed and the antenna length already adjusted.
It's the radios where you make the custom mounts and coax lengths that generally get "hairy" with SWR's. While pre-made antennas with coax CAN be adjusted to perfection, they are usually PRETTY close to good.
If you are planning on a custom mount, you absolutely want an SWR meter.
We have a $20 uniden CB and a $150 Cobra. Non-peaked or modified. They both get the same distance just about.