It really is shocking how little some people think about the cost to their bridal party. My best friend was recently in a wedding where her bridesmaid dress was $300 (and quite ugly, not something one could rewear), shoes were another $100, and she also had to pay for own hair and for a hotel room. I suggested that she search online for a used version of the same dress, which she found and saved her quite a bit.
For my own wedding we tried very, very hard to keep costs reasonable for our bridal party. I kept an eye out for when JCrew had a sale on their dresses and all of my girls were able to snag theirs for $70. I let them pick their own shoes and jewelry, and we put them up in a hotel room. My husband's groomsmen had it even easier--they just needed to buy a particular $20 tie and wear a white dress shirt, dark grey dress pants, and black shoes, which most of them had anyway and could use after the wedding if they didn't. Since we were married outside in Texas in May, we didn't make them wear jackets. Being outside, our wedding wasn't a super formal affair, but even if it had been, I definitely would have had the groomsmen wear basic black or grey suits that they bought rather than rent tuxs so at least they'd have something to show for the money they spent.