I think this is fine. For most friends, we do about $100-$150. Maybe for a really close friend I've done $200? Also, we are going to my husband's co-workers wedding. (Kinda, she's already married, this is a ceremony for show plus a celebration.) She's not a friend of his, just an acquaintance. We bought a $65 gift from their registry. I think the general rule is don't go below $50, and depending on how close you are to the couple, go up from there.