I just bought a whole heap of goodies off Bump, Baby and Beyond. They have all the top maternity brands at reasonable prices. Sizes can be limited for popular items though and bargain sell out quick so I recommend getting something if you really like it cause I've already missed out on several items by leaving it for a day or two.

A friend of mine, also pregnant with her second, has ordered quite a bit from this site and said their size charts are pretty accurate and the clothing is great. I'll give you all an update when my order arrives this week.