100 Day Celebration Money Amount

My friend had a red egg and ginger party/ 100 day celebration for her daughter which I wasn’t able to attend. I want to give her a money gift though. I know “8” is a lucky number, so $88 (double fortune) is common. The $88 seems a little high for me, so I was going to do $50 - but I would like to do something using the number “8”. Is $58 something that could be done or should I stick with $50?