For my wedding we just loaded up Costco, got some kegs, and paid a friend of a friend to bartend. Ended up being a fraction of the price than having a bartender bring in all their stuff.
I'm old. I remember drinking at incredibly cheap prices in dive bars (and I mean incredibly cheap for back then). Customers would flock to these places because they were cheap, and they'd make a tonne of money due to the sheer volume of alcohol sold. It doesn't happen anymore because we are more responsible as a society in some ways (read: the wowsers banned it).