transceiver fm-band
It will be cheaper to buy a CB radio than to make one.
You will find secondhand CB radio's in fleamarkets, ebay, classified ads etc.
You can purchase service manuals and books with circuit diagrams of many models of CB radio.
Saying "AM band" or "fm band" means nothing unless you say what country you are in. In the USA AM and SSB is legal on 26.965-27.405 known as midband. In Great Britain only FM is legal. All over the world people illegally use AM/FM/SSB/morse/SSTV/data all over 25-30MHz.
>It will be better if its a simple one.
All CB radio made in the last twenty years are the same basic design, frequency synthersizer, superhetrodyne receiver with 10.7MHz and 455KHz intermediate frequency, chip + quadrature coil FM detector, chain of transistor amplifer stages for RF power output, low pass filter.
Any design simpler than that will have bad performance in some way like poor receiver sensativity, poor selectivity, dirty rf output.