You can make some great savings with second hand gear, (although not always with so called 'classic' CB radios often selling for more than new radios!), but you have to be aware that you won't have a warranty and usually no come back if there is anything wrong with it.
You'll also have to think about what you want from CB radio to decide on what type to buy as well as accessories.
Do you wish to run mobile or as a homebase setup?
Running mobile can be rewarding in that you are not limited by location being able to travel about to different places with less QRM or interference. There's also the added advantage that you can drive to higher ground essentially raising your antenna height with the added benefit of further reach contacts.
Obviously you'll have to look at hooking it up to your vehicles electrics as well as mounting an antenna.
With a homebase setup you'll have to add the expense of a good power supply as well as coax cable and/or a homebase antenna. You could do the old trick of sticking a mag mount onto the proverbial biscuit tin but this really only worked back in the 1980's when there were more people on air, closer together and biscuit tins were still metal!
You can save money with basic FM or FM/AM only radios but much will depend on radio activity in your area. With a more expensive multimode radio you'll have the added advantage of SSB or sideband modes where signal efficiency is much better for further reaching contacts.
Then there's thing like SWR meters which obviously come in handy for when you install/tune your antenna.
As you can see things can soon add up cash wise very quickly!
There's nothing worse than seeing someone spend very little and not making contacts so give it all up and similarly you can splash out a fortune and still not make much contact so feel cash bereft and cheated too.
Radio interests are definitely better when you're in it for the long haul learning all you need to know about setting up a good station as well as time and often dedication to making contacts. If you're the sort that buzzes with excitement with the thought or actuality of making radio contacts then you'll do well.
I've left you with a bit to think about and wish you well with any decisions you make as well as future radio activity.
It can all be tremendous fun which is why most of here do it.
All the best,