blimey, can you be my sister-in-law if you spend that much?
years ago, my sisters and I made an agreement that we would only buy each other presents for our birthdays, not christmas as little sis had 2 DSs (now has 3) and there was too much money being spent otherwise.
little sis and her husband did buy us 2 (big sis and me) presents, as we bought for their DSs. Now big sis has a DD and the agreement stands, so I buy for the niece and nephews and they all by for me! 
i don't ask them to buy for me, but they do it because they don't want me to feel left out.
i buy for mum and dad, and for my nephews and nieces at birthdays too.
to put it into context, my sister got a necklace that cost £7 and my nephew got a couple of books (cos I get kids' books at cost, so it cost me about £6 for the two)
that's enough money to spend when you've got 6 birthdays plus mum and dad every year, as well as DH. and christmas on top.
presents are about the thought - not saying that you should reduce how much you spend, but really think about whether it's the cost/value you care about, rather than buying thm something they will really want/need.
to me, a stick of sure anti-perspirant costing £1.80 is worth more than a box of Thornton's Continentals (i don't like truffles)