Why not just go to a park, and have a picnic?
Are you happy to pay for food, or would you prefer for them to pay at a high tea?
These days its not unusual for people to pay for food etc at a baby shower, but I guess it depends on what you are willing to spend.

This is a tricky one as you’re asking people to pay for something & also expect a gift in return. It’s a large crowd. I’d be happy to bring a plate to share & go to a park

Im sure your friends wont mind paying $30. I know I wouldnt mind.

Could you just got to a nice park and get everyone to bing a plate of food?

I think you should have it in a local park, I think parks are beautiful for this kind of thing.
I was going to have mine in a park, but my parents have enough room at their house.
Most parks are free. We have a local Botanical Gardens – it is amazing in there, it used to cost money but now it doesn’t. The only problem is making sure that you get a spot, so perhaps get a friend to arrive really early and reserve a place for you to have it.

Good luck.

High tea would be wonderful for just a couple of friends, but for 30 perhaps something like a park or marina. Somewhere you can easily cater yourself.

I would suggest a morning tea in a park that has a play area for children and all invitee’s bring a plate for it. You can use the BBQ for boiling the water for Tea and coffee or alternatively take fruit juices iced tea iced coffee etc. There are load of baby shower games that you can play in the park like find the bonnet (first you have to hide it and manufacture clues) and i would also suggest lots of rugs for seating. With bringing gifts for the bub i would suggest not asking them to pay for a venue and high tea, and then that cash can go on the gifts for Bub