So...I have to say I get so annoyed with "proper" etiquette rules sometimes...especially when being proper amounts to making more of your guests unhappy.
For my wedding, my budget for hosting a bar is about $1500. I plan to put a cap on the hosted amount and once the cap is met it will turn into a "gasp!!" cash bar. I may even restrict the hosted bar to beer & wine so it last longer and the guests are on their own if they want to purchase hard liquor drinks.
I understand the IDEA of the etiquette rule that a cash bar is wrong...you wouldn't invite people over to your house and ask them to pay for drinks yada yada. But, if I'm at a wedding I would MUCH rather have the option to purchase an alcoholic drink than be restricted to no drinking. If I'm providing non-alcoholic drinks with dinner, it is my guests choice if they want to buy alcoholic drinks. Why is it so wrong to give your guests options?
I'm not saying charge your guests $5 at the door...it isn't a frat party, but I've had several friends rant to me about dry weddings and how they ended up bringing a flask, or (in the case of one wedding) a bunch of people running across the street to the store to buy a few bottles of jack daniels. I'm sorry, but for my wedding, the reception is going to be a fun, upbeat party, not a stuffy frou frou affair. I'm not going to cut everyone off and take the bar away because my wallet is maxed out. They can keep drinking if they choose to...and they don't have to run to the store for it!