DC are 5, 6 and 6. For Xmas, we have the grand total of £33 for all of them, with stockings costing £4 each. Total spend is therefore £45 for thre three. They are spoilt by my parents and this year are getting a big shared gift with loads of little things in it to open, so is as exciting as many smaller presents.
For birthdays, it varies. DTs had their birthday last week, and we spent £20 each, but this allows for a lot, we have a very good charity shop nearby with chikdren books for 10 for £2 (and great quality, wanted books too) which means we get a lot for our money. Freecycle and Gumtree means that usually we find a gift worth a lot more than what we pay (or even get for free) and our family overload them with gifts. DC3 however has his birthday this week, and is getting £15 spent, but that's because he only wants sme very specific things and we've for everything for that price plus some more token gifts, and he's very obsessive about this and that, so if we get him extra, it will make him upset/tense. They are having a shared birthday party costing £90 though, half paid by the ILs, which is going to overshadow the birthday presents as it involves animals.
This is due to temporary costs (well, they've lasted a few years) due to DH being unemployed and also due to having to pay for a lot of care and support for my DPs. This should be resolved in about six months, and then we will hopefully be getting them a lot more.
Although the presents might be cheaper in a way, because they are close in age and good friends, we usually get a large present (like a big craft hamper) for them to share, which means they get the excitement and their own things. DH's family shower them with gifts and we have many relatives and friends to ensure that they are always bursting with presents, which means we can pick carefully with our budget, because we know that even if it's only two gifts there, they will be special for them, and they will have a ton of other gifts too. We also have a friend who works at the ice rink so we get free tickets there sometimes, meaning we can take them ice skating or whatever for free.