i can list a multitude of reasons to make your own ice cream instead of buying it from the store, but it really boils down to two reasons:
1. it’s easy
2. it’s DELICIOUS.
(ok, really this can really be boiled down to ONE reason – #2).
since i try my best to stay away from corn syrups, i end up not being able to buy 98% of the ice in your average grocery store. breyer’s makes a few flavors of DS-free ice cream, and ben and jerry’s is, for the most part, free of devils syrup, but generally speaking, it’s hard to find a scround without corn syrup in its ingredients. (scround. hee hee.)
so, i requested an ice cream maker for christmas, and so far, i am not disappointed (and i’ve only made about six batches of ice cream).
i’m not gonna lie: the ingredients aren’t necessarily cheap. my go-to chocolate recipe calls for 3-1/2 cups of heavy cream. 2 cups is anywhere from $1.99-$3.75 in the store. add in the sugars, whole milk, and cocoa powder, and it can probably run you $7 for a couple quarts. but considering a pint of ben and jerry’s is $4? i’ll take my homemade! (you can also lean more heavily on the milk instead of cream, but it won’t be as creamy.)
some recipes are a little more complicated, especially those calling for eggs that need to be cooked, but you can find egg-free recipes (i love you, ATK, but the easier the better for ice cream). my chocolate recipe is milk, cream, cocoa, sugar, brown sugar, and vanilla. mix together, put in ice cream maker, chill, eat. total prep time is, at most, 10 minutes. the hardest part will be waiting for it to chill down enough. if you prefer soft serve, you can eat it right out of the maker.
at this point, after i’m done making some ice cream, i just rinse out the ice cream maker container and throw it back in the freezer so it’s ready to go for the next round. 
next on my list of ice cream flavors to try: peanut butter chocolate and cookie dough. when spring comes, i’ll pick some raspberries and strawberries and make fruity ice cream.