Backyard wedding

It really depends on how you do it. some "backyard" weddings end up being about the same or more expensive depending on your vision.

Food and venue are big ticket items. So food you may have to look at different catering options and requirements for food safety for guests. Venues have the dance floor, stage, lights, sound system, building/tents that you will now need to rent. Bathroom facilities, decor, floral, etc.

I had a backyard wedding and had to rent a bunch of items, I even DIY'd a lot and all of it still came out around $15k.

Tbh, most times it's just easier to leave it in the hand of vendors. There's SO much that goes into a backyard wedding, and it ends up actually being more people and issues you're dealing with/trying to keep straight. All-inclusive venues are your best friend if you're wanting to reduce stress. They will provide a lot of the things you need all under one roof (so only one person and one contract to deal with). For example, our venue provided the ceremony and reception space. They set up and tore down the decor and the chairs for the ceremony. They provided the chairs, tables, tablecloths, silverware, servers, bar, bartenders, catering, and music for the reception. They set it all up, tore it all down, and provided a day-of coordinator to ensure everything ran smoothly. If you do a back yard wedding you are going to have to find vendors to handle all those things. Here is a list of some of the things you will need to do and people you will need to hire on your own if you have a backyard wedding: hire servers and licensed bartenders, stock the bar, provide plate ware, silverware, tables, chairs, tablecloths, hire a caterer, provide a way to ensure food stays at a safe temperature, have someone to empty trash as it becomes full, find a way to provide music, have an inclimate weather plan in place (ie, if it's cold you'll need heaters or if it rains you would need a backup indoor space or rent a large event tent). If you are having dancing, you will need to rent a dance floor to make the ground level and safe to dance on. You will need to get event insurance in case anyone is injured on your property. You would need to figure out a bathroom situation. Will you be allowing all your guests to traipse in and out of your home to use your restroom? And if so, who will be in charge of managing it (ie, refilling toilet paper and paper towels, emptying trash, cleaning throughout the night to ensure sanitary conditions), and also what is the backup plan if the toilet becomes out of commission? (with heavy, repetitive use, this is a definite possibility). You will be responsible for setting everything up and tearing everything down. You will need to provide parking for everyone. And you will need to check on local laws/regulations regarding hosting an event (ie, any noise restrictions, hours events are allowed, any permits required, etc.). I'm sure there are many more things, but this gives you an idea of how much goes into hosting a backyard event. It's usually much less stressful to just hire licensed vendors and let them handle the logistics of ensure the night goes smoothly.

A lot of this is going to depend on both size and formality. Thirty people for a backyard BBQ is a lot different than 120 people for a sit down dinner.