Recommend a larger style radio like Galaxy 929 or like models or even Cobra 29, 148, Uniden PC76 or 78 any like these radios. The smaller ones are nice, but not as good for range and quality, but it also depends on what you want to use it for. Is it just when you go wheelin with your buddies? If so get a smaller one. You'll usually never be too far away from each other to get out of range. Do you plan on using it for long road trips? Then go for the larger radio with the better clarity and distance.
As for antenna's, I only recommend Wilson steel whip style antenna's. Fiberglass whips are good, but not as good as a steel whip. Steel whips are also a lot more flexable for offroading compared to a fiberglass which can break much quicker trying to get underneath that branch. Magnetic mount, depending on if you like your paint job or not. And for those that want to suggest putting a piece of cloth under it to prevent scratching and rust, WRONG. Why? Because the magnet is the ground side of the antenna. Placing a cloth between it and the vehicle keeps it from making a true ground, hence more static in your radio, lack of distance both receive and transmit side, extremely hard to get your SWR's down and lets not forget you don't want to be keyed up when lightening strikes it. At the same time, hard mounted antenna's might not be what you want because they require drilling holes, but makes a much better ground than a magnet.
As for price, yes a Walmart or Radioshack special with antenna, between $40 to $100 dollars. As you look at bigger better equipment, the price goes up.
Any truck stops in your area? Check with truck drivers and see if there is a CB shop around. They can have good deals on used radios, where you can get the bigger radio for the little radio pricing, depending on what has been done to it. As you're new to CB's, you can also get them to set your SWR's for you so you don't have to buy your own meter to do it. Some radio's come with SWR meters built in, but don't always trust them. They won't stay calibrated like an external meter will.
One last suggestion for anyone new to CB's. When you get it hooked up, don't grab the mike and key it up. Turn it on and listen to how others talk for a week or so, then ask for your first break. People don't talk on them like you see in the movies with BREAKER, BREAKER 1-9, BS. Start then and you're likely not to get a response from anyone then you think your radio is messed up and you just got yourself the name of MUD DUCK on the radio.
What you need:
As for what you need, the radio, an antenna, 18 ft of coax if the antenna doesn't come with it. The reason for 18ft is to make up the difference in the length of your antenna since you can't mount it as high like you can a base station antenna. Any extra coax should be hidden somewhere, like under your seat in large loops. Small loops in coax can raise your SWR's as it will act as a second center load for your antenna. If you get one used also make sure it has the mounting bracket. Depending on your hearing and where you mount your radio, you may also want to pick up an external speaker. Proper wire connectors to hook up the ground and positive wire with and any tools and hardware to mount the equipment with.