i paid for my bridesmaids dresses and plan to pay for the accessories, shoes, jewellery and hair and beauty appointments too. when i was bridesmaid for my friend i got mine paid for, i would say it would be tradition that it was paid for rather than the other way round!! i dont think it should be their responsibility. imagine if your best friend couldnt afford to buy their dress, then they couldnt be your bridesmaid...
i watched an episode of dont tell the bride where the men plan the weddings, he had a budget of £14,000 and didnt have enough money to buy the bridesmaid dresses - i thought it was a bit of a cheek- since they are a really big part of your day!!!