L.L.
I have 2 girls, but my husband cuts his own. Clippers are really affordable ($30-$40 gets you 5-6 years worth of hair cuts) and it is super easy to do. Start with a buzz cut and then you can play around with different stuff as the weather gets cold (that way, he is wearing hats more if he has a bad cut, and it grows out quick any way)
I have been cutting my daughters' hair since they were born - I also cut my own hair (started in college when I was to broke to afford to pay for it). I have had some bad cuts, but then I have had stylists give me bad cuts too. Plus if you learn now while you kiddo is young, he will think it is normal by the time he is a teen and cares about these things.
Good luck!!