Seeing as imported cottons from India were a big deal in the 19th century, I don't think it would be too far fetched to have a bustle gown made out of sari fabric. It is much easier for me to order serious quantities of fabric at a much lower price from India than anywhere else I have found online. I have my eye on a dark navy blue cotton with a small scale all over floral print in white. I think navy and white is a good period correct color scheme, even though the dress will now lean a bit more "seaside", rather than "train travel" as I had originally planned.
I would use the excellent border design on the sari fabric for the "vest" part of the bodice, the cuffs on the sleeves, and the hem of the back waterfall overskirt. If I have enough fabric to piece together some ribbon-ish trim to add to the pleats on the under-skirt I will use the sari fabric, if not I'll use a matching navy blue cotton.
I am growing more and more happy with this design! Although different from my original plan, and much more suited to summer, I think it will turn out really fun! I am already dreaming of a Batternburg lace parasol and some fine ivory crochet mitts as accessories with this dress! I hope to order the fabric this week and then get started as soon as the fabric arrives from far away India. Which could take a while, but for the savings, will be well worth the wait!