Hi,
I'm new to MN and this is my first post. I decided to take the plunge as I'm in knots over this issue and have found lots of advice on MN in the past.
We have an au pair. She is the same age as me (which, yes, was a mistake and is very weird!) and for various reasons myself and DH really don't like her. However, the children do and she does a great job and we only have a few months left to go 
It is my DS's birthday soon and AP's birthday is the same day. We have bought DS a bike which our family have contributed to. It was expensive - about £230 - and we don't usually spend this much but he really needs a bike as he has out-grown his old one.
I don't usually spend more than £30 on an AP's birthday (we've had a number before) although I usually get a box of chocs and some other cheaper bits and bobs so there are always a few things to open. On this occassion though, £30 is going to look measly compared to DS's bike!
As a family, we don't really go all-out on birthdays but the children are allowed to choose a treat. DS wants to go go-karting which he really loves. In previous years, we only pay for the children to participate - if DH and I took part, the costs become ridiculous and DH and I prefer to watch, take pics and cheer from the sidelines. I'd rather the AP didn't join in either - as we are the same age I expect her to stay on the sidelines with the other adults!
My first questions, is am I wrong to worry about the value I'm spending on AP (in comparison to DS's bike)?
Secondly, do you think it's ok to treat DS to his go-karting on the evening of his birthday but only include the children (me, DH and AP will watch).
Afterwards, I thought we'd go for a meal and I'll obviously make two cakes!
Thanks in advance everyone :)