Let’s look at average cost:
Tux Rental ($200 – $250)
Shoes ($200)
Special Socks ($50)
Hotel room for the night before the wedding ($200)
You may not have to get all of these things,
but be prepared to spend at least $700 as a groomsman.
If you cannot afford this, just say no and offer to help in other ways.
Help him pick out his outfit, help the groomsmen to coordinate their outfits,
offer to be an escort or usher for the wedding, offer to drive him to the ceremony,
and pray with him and for him.
There are lots of ways to be a friend, even if you can’t be in the ceremony.
He will appreciate your honesty.