I paid a bit more for my setup, just because I really wanted it to have a certain look and feel. Here's what I'm running in my JK.
Cobra 75WXST - $85
Fire-Flex coax - $20
Spare Tire Mount - $20
Firestik Stud - $8
3ft Firestik - $20
Microphone Mount - $30

The setup is really unobtrusive and I think it looks nice, but everyone is going to have their own opinions on aesthetics. Seriously though, shop around for a bit before committing. There's a zillion combinations of radios, antenna lengths, antenna types, mounting locations, etc to think about. My mounting location (spare tire), for example, is not ideal when it comes to signal propagation. A hood mount would be much better.

Certainly can get out the door for under $100. Here are two examples from Cobra alone. Here's one for $30, even. Factoring in installation by a pro, I'm not sure. I don't know what that would cost. It's incredibly easy to just do yourself, though, particularly if you're going with a cig lighter as your power source and a mag mount antenna.

Take a look at the Cobra 75 https://www.amazon.com/Cobra-75WXST-40-Channel-CB-Radio/dp/B00005N5WW/ref=sr_1_5?s=electronics&ie=UTF8&qid=1483037249&sr=1-5&keywords=cobra+cb+radio

This is the radio I have installed in my X and it takes up very little space. I was able to tuck the small metal box that the power and antenna connect to up under the dash to the left of the glove box. Just pop the glovebox out and find a good place to ziptie it down. The cable for the mic/handset routes out near the passenger footwell and I have the mic hanging from the rearview mirror where it's easy to get at.

I'll try to grab some pics of my setup later if I can.