I have four friends (two couples) who've gotten married on the cheap and they've been the best, most meaningful ceremonies I've been to.
B&A - Family Farmhouse Wedding
B&A took their nucleus families (parents and the one sibling for B) to Jasper, where they stayed in a nice, but frugal hotel, did a bunch of hiking and did a civil ceremony in a lawyer's office in the company of their parents and sibling.
When they got back into town after a weekend away, they hosted a potluck/bring your own outdoor games reception for all of their friends - literally everyone they liked was invited out - to join them A's aunt's family farm. It was fantastic, and cheap. None of us brought gifts, just food we made ourselves. Lots of dogs, lots of friends and lots of fun.
J&A - Community Hall
J&A got a small (75 people) church wedding and rented a small (100 person capacity, about the same 75 people from the church) community hall for an open reception. They had a cash bar to help cover their costs for the catering (really cheap college-style buffet food, which fits their personality as a couple just fine) and a cake made by one of their friends. A works as a video game distributor and "borrowed" some of his demo stations to set up Super Smash Bros, Mario Kart and Mario Party play "booths" for everyone to enjoy. A friend was the DJ and no one was expected to bring gifts.
EDIT: OMG, I almost forgot about one of our favourite parts of this one! J&A went to Costco and went hog-wild on the candy aisle. I think they spent maybe $50 but got more candy than everyone could eat. We all got to take some of our favourites home. It was a smashing idea.
Another fun option, though I won't call it Mustachian because the main wedding party went on a trip to visit the bride's family in Greece, was N&G.
After their return (where I assume everyone financed their own way - the families are both quite frugal ordinarily), they had an open invitation to bring food and drink to one of their parents' house, and set up a projector and screen their dad owns to put on a looping view of the pictures from the trip. A friend was the DJ and they ordered in pizza. We all chilled in the backyard, chatted, threw around a frisbee and learned about the trip.
Personally, I think having a "bring food and your drink" party in a nice hall, park or house is a nice way to go. Ceremonies aren't necessary unless one partner really really wants it, and even then I'd recommend keeping it to a small number of attendees. Something that really struck me about the celebrations above is that they felt a lot more personal and happy than the big waterfront hotel-hosted shebang. I felt isolated, surrounded by stiff family drama and crying babies, and not at all able to connect with family or friends being sat at a numbered table. With the ones above, I could mix and mingle as I wanted, approach the bride/groom/wedding party as I wanted and chat with people I'd never met before about how we're connected through the happy couple.
Plus, I feel with a more loose-formatted gathering, you have the option to really share who you are with your friends and family, instead of holding up some fake fairytale-esque image you've paid someone else to spritz up for you.