Welcome to the forum, thursdayrecords. It is a good idea to add your location and zone to your profile so we know the conditions you are gardening in.
If you have time you can save yourself some money if you make a lasagna bed and put 4 inches of potting soil on top if you want to plant sooner.
https://extension.oregonstate.edu/lane/s ... 2015_0.pdf
Otherwise Mel's Mix works
one part peat moss
one part vermiculite
one part blended compost from multiple sources. (usually you have to have 5 different types of compost like composted manure, mushroom compost, black cow, black gold, leaf mold, composting facility)
Peat moss (3.8 cu ft) and vermiculite (4 cu ft) can be purchase in bulk bags from an agricultural supplier. Most companies will deliver if you order at least 50 bags of anything in total. Peat moss is compacted so one bag will decompress to twice the volume so one bag of compost will need 2 bags of vermiculite and 2 parts of blended compost.
It can be mixed on a tarp with a shovel or if you are doing a large volume, rent a small cement mixer and mix the components in the mixer. Moisten the mix as you add it in. Peat moss is very hard to wet and you want to avoid dry spots.
If you have a local composting facility, ask if they sell a nursery or garden mix. It usually has the compost, sand, soil, and sometimes manure in it and it is ready to plant. Ask for the soil analysis first to make sure it is not too alkaline.
Mel's mix can get pretty pricey if you are going to fill a lot of beds with it, but you can do sheet mulching on the beds and just make enough Mel's mix for the top 4 inches in order to plant it sooner.
People here have been able to get kitchen waste from local retaurants but you will have to screen out some of the unwanted stuff like plastic wrappers and styrofoam. Coffee grounds and filters are o.k. It is better if you provide them with the containers with tight fitting lids and you pick it up promptly. Let them know when you don't need anymore. For browns you can ask the local tree trimmers for chipped material. Make sure they don't have weeds or use trees like black walnut. You can get a mountain of that delivered usually for free if they are in the area as long as there is good access. Whatever you don't use for the browns you can use as mulch or for the start of your own compost pile. Stables and farms are good places to get manure for the compost pile but fresh manure should not be used in beds you are going to plant right away. They need to be composted or aged at least 120 days before harvest. Manures may contain weed seeds so you want to compost that as well. Compost piles need to be at least 3 ft tall and and longer than 3 ft with the right proportion or greens, browns, and water to heat up well. The more frequently a pile is turned after the first week, the faster compost gets done. The downside is that the organisms are relatively dormant in winter and composting happens very slowly. The activity speeds up once the weather warms. Most people start the compost pile in the fall and let it sit over winter and slowly decompose.
Happy gardening in Hawaii. Gardens are where people grow.