It's relatively inexpensive to get into the hobby (truly, in its simplest form it's just a radio and an antenna, you can really TX (transmit) on anything). If you're just looking to get started (and in the US) you can get your technicians license (three classes of license, tech general and extra) and start transmitting and building. US is one of the only countries that says "here's a license and a call sign, go have fun".