#1 way to cut costs at any wedding is having fewer people. DWs make that much easier than hometown weddings.
Now, once you start having as many people to your DW as you would to your hometown wedding, you really aren't saving money.
The other way to talk about it is in terms of VALUE. My sister had a wedding in our hometown for $20K. She had 150 ppl, decent food, and a 3 hour celebration.
I had a wedding in Mexico for $20K and had 50 people, 2 nights of great food and drink, daytime activities, and 3 DAYS of celebrating.
How would you rather spend $20K?