Yes, that is also a great option and a great free alternative.
The only thing to note with that is that you might have customers land on your store, fall for your products, want to purchase and then find out when they're ready to buy that they can't continue with the checkout. Although this answers the question of blocking certain countries this could potentially lead to some negative store reviews.
There certainly are ways to do this. I actually wrote out a forum post last week that goes into all of the specifics of what would be needed for what you're looking to do.
If you click this link here you will be brought to the reply where I list all of the options. Are you able to read over those to see if that's what you're looking for or if any of those would work. If you have any follow up questions please don't hesitate to let me know!