I had silk flowers at my wedding. My bouquet has all white and pale pink roses with a red (for each of my parents) and my bridesmaid and moh had bouquets with purpley/blue hydragea and lilac blooms, they were not overly large at all. I had a May wedding and had spring colors.
My bouquet was teardrop shape with greens and streamers (for my mil
) trailing on the bottom.
If saving money is the object, lesser flowers in your bouquet and maybe filling in with really pretty fern and baby's breath will help. As for your attendants, I don't think they need to be overly fancy. Maybe adding ribbons to the single flower idea will help dress it up?