Oh man that a large number of people and for this number of people I wouldn’t bake myself.
I would do fruit platters, popcorn is nice and cheap, part pies and spring rolls come in big cheap boxes, plates of chips, platter with sandwiches, platter with cocktail sausages, cubes of cheese

Home made pita chips from pita bread cheap dip and pop corn popped fresh from kernels

Sandwiches, party pies and sausage rolls, dim sims etc

Homemade options would be cheaper small muffins little quiches and wraps ect little finger foods are good idea

Scones are cheap to make or buy. Then you just need some jam and cream which are also cheap. These will look very nice on a table and are very filling too. I’m sure your guests will love them.

I like to make a cob loaf. I have a bread machine so I make the loaf st home. Fry up bacon and garlic. Stir in a chunk of creamed cheese and tub of sour cream. When melted add half a tin of creamed corn. Cut top off loaf and scoop out bread. Fill with bacon filling, top with grated cheese and bake 20 mins. Use scooped out and cut off bread as dippers. Yum

Fairy bread, choc crackles, honey joys, vanilla cupcakes, gingerbread, jam drop biscuits, jelly,

Ive heard of watermelon pizza with fruit toppings and also maybe Lebanese bread cheese and tomato pizza..

Sausage rolls (super easy to make your own if you have time!), party pies, cocktail Frankfurts, fruit platter (watermelon is a great base and super cheap!) crackers, fairy bread, chips, lollies, cupcakes, jelly, popcorn!

Make as much as you can yourself instead of buying ready made, and delegate if you can, it makes the biggest difference. I only delegate to family that offer (they always do), don’t be afraid to take it up. I only ask them to bring one thing each, but makes the biggest difference on my end.

You can’t go past cupcakes, very cheap if you buy the home-brand cake mixes.

Mini sandwiches, Sausage rolls, cheerios/frankfurts, fairy bread, cut up fruit, popcorn, jelly cups, or even cheapy iceblocks (depending where and whether u have a portable freezer of course).

I make mini quiches – everyone loves them! Quite inexpensive. Just Bacon, Eggs, Sour cream, cheese and a bit of milk or normal cream for the filling, puff pastry for the cases and you are set. They can also be served cold so prep is easy.

Another option depending on time is to get some pre-prepared food on platters. I have used some big savoury food platters from places like Costco and Woolies for meats and salads etc. Then cooked up my own food too – with both their food and my food – there has been plenty of food and choices for all tastes.

Ribbon sandwiches are lovely for afternoon tea and home-made mini quiches are delicious,best of luck with so many people!