Building and launching your own rocket? Space is hard. A lot of fortunes have been lost by people who have underestimated the difficulty and cost of doing it themselves (and over-estimated investor confidence). (Musk and Branson have deep pockets, so they could deal with it, but it's harder than they thought, too.)
But other people will launch stuff for you. According to the Wikipedia article on CubeSats, a basic CubeSat could be constructed for about \$50,000 and launched for another \$100,000. And you'll probably have a 2W transmitter that you'll have to communicate with on Earth. Beyond that it's all regulatory. That's specifically a CubeSat because it fits with other CubeSats into a standardized launcher, which is usually carried up as a secondary payload. That batch launching contributes to the low price.
https://en.wikipedia.org/wiki/CubeSat#Costs
But you might get it launched for free through NASA's CubeSat Launch Initiative if it helps to advance their work.
https://www.nasa.gov/directorates/heo/home/CubeSats_initiative
Then there are licensing issues.
https://www.nasa.gov/content/cubesat-launch-initiative-resources
Not cheap or easy, but still cheaper and easier than one might have thought.