My B-day gift amount nowadays is $50. I have 9 DGkids, ages 11 (only DGS) to 29. Yes, that's 8 DGD's. After age 6 I stopped buying the girls clothes, instead DH and would take them out for lunch and shopping for a new outfit. Now that the girls are older and 6 live out of state they receive a $50 check for their B-days, nice and simple. DGS 11th B-day was last month and his gifts were a Rutger's t-shirt ($10-his Dad our DS#3 is a grad), we went shopping with him for a computer game ($30) so when we were leaving I gave him $10 as spending money.
My sons and their wives also get checks for their B-days but for Christmas each family member gets a personal main gift and maybe a few little items.
A whole new ball game is in the works as far as gift giving goes, last year we got a new DGS (married one of our DGD's) and 2 new DGD's coming next year as one DGD is getting married in June and another in the Fall.