Hi there, bridesmaids dresses can be very difficult to shop for if you want something that doesn't make you look like a frosted cupcake. Searching for a black cocktail dress around $200 shouldn't be to hard. I would think that a lot of local boutique would have some dresses that meet that criteria.
I, for one, have a few styles at my shop, Phlox, that fall in the category you are looking for. You can always stop in to see what I have available. If I don't have your size, it may be possible to order it for you.
Having said that, most small local boutiques won't have a large selection of black dresses. You might have to hit a few a shops before finding the right one. Other dress heavy stores to try are Mabel & Zora, Parallel, Frances May, and then maybe, if you still haven't found anything, Nordstrom.
Good Luck!!