I think your numbers are right on, even though we’ve also seen the overly-generous parents with too-expensive gifts. Tough call, but a quality present at $20 is a very decent gift in my mind, even for a close friend.
Also, I’d say the dollar amount should go up if other siblings are invited. Maybe $10 more.
We’ve tried to tell people that we don’t want any presents at all for our kids’ birthdays, and that we just want their company, but too many still end up bringing gifts. Really, kids these days have way too much stuff.
Regarding the wrapping, we like to use gift bags that we all reuse over and over and over again. Agree that wrapping paper is pretty wasteful. Kids might recognize the re-return of the gift bags, but they seem to enjoy recollecting when they last saw the bags. It’s only an issue if parents make it an issue.
Yes, you can re-gift, too, but best to do it with kids from different playgroups, if possible. 🙂