Buy online. Buy in quantity if you want to save money.
Even if you boutique buy, a quality place like Midway will probably save you money over a gimmicky vending machine. And no "facial scan" that the machines supposedly do as part of their security theater.
Bulk is the way to go. I buy cases of 8 lb jugs of powder and 10-20k primers at a time. Of course I shoot 8k+ rounds every year.