Wedding Dilemma

My brother in law is getting married again and asked my husband (his brother) to be in the wedding. Im not sure what the role is but it requires a tux rental. My assumption was if someone asks you to be in their wedding that they are supposed to pay for it. Is this not how it goes? Money is stretched very tight right now since we are both technically unemployed. My husband just recently lost his job and I start my new one tomorrow. We just can’t justify spending suit rental for one day when we have bills to pay. He is considering not going if his brother won’t pay or come up with half. Are we wrong in doing so? TBH I don’t even want to attend anyway. He also said no kids and that means getting a sitter.

My husband said he wouldn’t mind buying the suit if it came down to it but he hates the color. He can’t justify buying or even renting something he hates just for one day. I believe the suit rental is $300 and he wants me to find a dress to match. The colors are a champagne/beige color. So its more like 300+ for just one day. I didn’t go to the fitting im only describing what my husband said. He has good taste so if he said its ugly its ugly😂