Because of how the world is changing and the way we live, of course, my advice is not to go with the biggest supplier out there. You can read here more about the food and beverage industry and what trends are paving the future.
So what about how we get our food suppliers? Do we go big or small? The answer to this is that we go small and local as much as we can.
A really big plus for your location is to advertise how you are helping others grow around you. New generations are way more mindful of where they drink and eat.

Vegetables, fruits & animal products
My advice is to go to your local farmer and get all the vegetables, fruits, meat you need. Make sure you advertise this so you will also grow in revenue and number of guests.
If you are living in a big city maybe going to an actual farm is too far and time consuming, but you can instead co shop at organic markets and/or bio markets. The most important point is that you should make a connection/ contract with the producer, not just a second party that only displays the products, go straight to the source.
Booze
Now here you might not have a choice. The mainstream booz you will get from a licence distribuitor.
In the area you have the chance to help small breweries, wineries, distillers. Make sure they have all the credentials and they do not break state rules.
Present to your guest a part of your country or city through them.

Other drinks
Who thought that natural juices can be 100% natural? You can make them by yourself, though this might be time consuming and not your goal.
Instead of buying an ordinary apple juice that is mass produced, try opt for a small business that makes their apple juice in your city and that you know is good, delicious tasting and more attractive for your guests.

Even if you see the cost getting a bit higher, nobody is saying that you can’t increase your prices.
Instead of focusing on the budget, invest more in a marketing campaign that can show what how your business is helping others around you as well. Plus, a contract like that doesn’t mean you have to loos money. You can play that in your favor as well.
Other products
Go handmade and environment friendly.
Why do something like that when you can buy everything so easy and be like the others?
Well that is exactly the reason why. You do not want to be like all the others. You want to stand out!

Support others around you!