ReseevoirDogs not at all, as a guest you can recycle outfits and shoes, do your own hair, stay in a cheap B&B rather than the hotel of the bride (which is ALWAYS expensive) etc.
OP YANBU why are you friends with a person who treats you like this?! 
I have a friend who got 'demoted' from maid of honour to regular bridesmaid because, when her DD was 6 weeks old she said no to going bridesmaid dress shopping 2 hours away. Aside from just having recovered from a EMCS and infected wound, she was breastfeeding, had an oversupply (so lots of leaks) and still a heavy bleeding from the birth and was nervous about staining and leaking onto any dresses. Plus her DD didn't take bottles and wasnt a good napper so she didn't fancy traipsing her round this wedding shop.
This was 18 months BEFORE the wedding!
You'd think she'd murdered someone for the reaction her refusal got. The 40 year old groom was even texting her telling her what a crap friend she was to the bride
imagine being so self absorbed you think everything revolves round your overpriced party, even someone's newborn baby and their own health!
IIRC that particular bride also had monthly meetings with her bridesmaids for the 18 months running up to the day!