In our house Santa brings one gift only per child. This is not something massive. Think £13-£16 tops. When dd was younger it was even less. We also buy our kids a bigger gift, quite a few little gifts and they buy each other a larger and a smaller gift.
I agree with JavelinArse when they say You are not a failure, children are hard bloody work! I think it's worth starting to talk to your children about the importance of appreciating that it's the thought that counts when it comes to gifts and that they are much more fortunate than many children.
As I wrapped gifts (literally a sea of small nice things collected over months) I watched news items of kids who had nothing. No clothes or even food. Toys were not even mentioned. It is not possible to fulfil all the wishes of our children. It is easier, and in the long run better, to give children realistic expectations of what they may get for Christmas (from us as parents or from Santa - if he calls at your house).
I also agree with TooHasty when they say Christmas is so over-hyped these days, it is nearly certain not to be a 'wow' day!
It is good to find fun things the kids can enjoy that do not cost too much. Making cakes, going in the bath in their swim suits together with all their new bath toys in the middle of the day, whatever it is they like. My dd wanted to clean the car the other day (she 10 so I let her) so loved it.
I was worried our son would be upset as he can be quite demanding. He is newly adopted and had some expectations about Santa bringing all the gifts at Christmas! I made sure he knew this was not the case and he would not get all the things on his massive list! He literally watched telly on CITV and shouted 'I want that on my list' 'I want that on my list' every few minutes!!
I was nervous, but it has been OK. We got things he had said he wanted and it worked out OK but it could have been a different story!
Our son just needs to learn.
Sometimes a variety of smaller cheaper items are easier as there is more chance that one of them will hit the spot. But I do think kids in general need to cut out the moaning, mine, yours, anyone's kids! And I think if they really do not like the gifts they can take them to the charity shop and start making realistic plans for next year!
But do not beat yourself up, you are a caring mum doing your best. I hope someone got you something nice! 