Expensive Bride`s Maid Dress

A friend of mine told me ages ago that I was one of her b/maids. When we went shopping she chose really expensive dresses - I pointed out that I couldn`t afford such a price (especially as I`m not going to wear it again) and she said she would subsidise me. Now her wedding planner just called and wants the full price (which is a LOT!).
There`s no way i can afford that much, especially as I`m not likely to wear it again. I can afford about 50-60% of the full price. The wedding is in 2 weeks. We`re 5 maids and I know the others can afford it. What do I do? Please help...