it depends completely on who you have invited. People who can afford it may give you $500 or $180 whether they show up or not. Some people cannot afford more than $36 or $50. And many people give gifts. It would depend on your circle of friends, relatives and very possibly what the “norms” are for gift giving in your community.
i have heard that you are supposed to pay in relation to how much you “cost” the host, so if you are three people who came and ate, you would pay more than one person who didn’t attend. Not really sure how someone cheshbons that but I have no doubt there are many here who have more accurate details on the subject.