Can I get some help from you folks?

I need a summer dress I can use as a bridesmaid dress for a destination wedding. The wedding will likely be in November (no date yet) and the dress will need to be either in a shade of blue/turquoise/green or else coral. It needs to be a bit more casual (think beach wedding) so not shiny or stiff. There will only be three of us as bridesmaids so we will go with whatever works best for the majority colour-wise- the bride isn't picky. The dresses don't need to be identical so we are all finding our own.
Cost under $100, good shipping times to Canada, and decent return policies (in case things don't fit) are also crucial.

I've exhausted my local options so I need to order online and snatch something up before all the summer stock is gone. I'd appreciate some advice, direction, assistance, whatever you can offer.

Thanks!

Here's a photo to give a general idea of my body shape.

Oh, and I should mention I have *never* bought clothing online before so treat me like a rank beginner (which I am).

So one of the other bridesmaids has a dress and I've added a picture. It looks like coral will be the colour to go.