Yes Vistaprint does have many designs and their product filter makes it easy to zero in on a design you like once you pick the size of the brochure, number of folds and paper quality.
For brochures the lower limit I believe is 25 with the maximum being over 20,000. Other products have lower limits but that obviously doesn't help you here. The reason for limits is that it does cost Vistaprint money to setup your order for printing so anything lower than 25 prints isn't worth there while financially (they would loose money).
If you want a sample of what a Vistaprint brochure quality is like you should go ahead and order the Vistaprint free samples kit. It has a brochure in it. Else you could try calling customer service on the phone. I find them to be pretty helpful and they may allow you order just a few different copies if you truly are going to order several hundred in the end.