No you're not wrong to be upset...they are wrong in their approach to the hen night, but there again you have said you think it value for money compared to other hen nights you've heard of.
Say if you go, you will not be forking out for wedding present, as the £100
is more than you can afford at the minute, so it's either hen night or wedding
present.
I would have said no, given their attitude, even if it is my cousin..speak up!!