I have paid for literally every baby shower I've been to (A LOT!) apart from 1 that was small enough to be held at home.
I have no idea why people are so weird about feeling they are paying "for" hen parties/baby showers etc. as though they are doing some sort of massive favour to the hen/mother to be. What you are almost always paying for is the activity (x) whether that's a hotel room, a meal, etc. Why on earth is that weird or entitled?
The hen/shower might be the REASON you are doing x but you are just paying for yourself. I've never been to a hen/baby shower where anyone has made a profit - just where venue charges £20 for afternoon tea, therefore all guests pay £20. Exactly as they would if it wasn't a baby shower and they were just meeting at that venue for a catch up. Very few venues will just let large groups of people use their facilities without buying anything. If you'd be happy to just meet up with a friend normally and pay for your own food/drinks, why is it suddenly some sort of great imposition just because it's for a specific reason?
And if you're not happy to pay the set price, just don't go! It's an invitation, not a summons, to trot out the MN fave. If you're going to sit there begrudging paying the cost for your OWN MEAL then I'm sure the mother to be would just prefer you not attend.
It's a weird MN specific thing - in real life I have NEVER heard anyone moan about paying for themselves at any hen/baby shower/birthday meal etc. I can't imagine how entitled you'd have to be to assume that the bride/mother should pay for the pleasure of your company! I've been to hens where there were more than 30 people - that would be £600 at £20 a head!