No idea why so many people are acting as though they've never heard of a baby shower before yet feel qualified to give advice
Ive been going to them for at least a decade, they can't be that new.
However most of the ones I've been to have been at venues (pretty much all afternoon tea) and have paid for myself at every single one, there's never been the slightest expectation the host or mum to be pays. No idea why people find this grabby, it's exactly the same as if you met at the pub for a meal for your birthday or something.
If people can't afford it, they don't have to come. If they come they are only paying for their own meal, that they themselves are eating, like in pretty much every other social situation where a group of people meet at an external venue.
Shock horror to lots of MN, I know, but some people actually like their friends and enjoy spending time with them, so don't begrudge paying a few quid for some tea and cake, which they will also enjoy, to do so.
Perhaps its hard to envision when you're middle class and middle aged but a lot of people dont have big houses so it's the norm to pretty much always meet at an external venue where, yes, you're usually expected to pay for food and/or drink to use the premises.
Just find somewhere nice, put an invite out to see how many can come and tell them the price, make sure you get people to pay upfront and in full to avoid you getting stuck with any drop outs. Put a few balloons up, up to you whether you want to play some games (there are lots of ideas online)or just chat.