It very well might be, if you value publicity for your hobby, the greater reach might be worth it to you. If you can get 10,000 readers instead of 90 readers because your links are shareable...

If we think about potential dollars, though:

The bottomless pit isn't very deep, it's a few dollars a year.

If it nets you one single short-contract offer (nevermind a job) or worthwhile contact because someone found your work, it'll pay itself off many, many times over. Let's say one person found him and offered him a $3000 contract to do some electronic thing for a week, well, then the cost of the domain and hosting won't matter for the rest of his life.

The mere fact that this guy has an oscilloscope out means he has skills that someone might want to contact him about in relation to his blog.

Limiting yourself for want of a $10/year domain name is probably not a great idea, and again, it's something I learned the hard way.