This should help you:-
http://www.flowers.org.uk/public/display_purple_colour.php
If you click on each flower available in purple, it will show you what they look like and if you switch to the "what's available when" option, it will tell you if they are available in October.
Your florist really should have asked for a photo of your dress so she could advise you which flowers would compliment it best. If you dress is elegant and classy, then the flowers should reflect it i.e., calla lilies, lisianthus, orchids, roses etc. If it's cinderella style or fairytale style, then country flowers go best such as anenomes, freesia, gypsophila etc. Did she show you any bouquets that she has already made for Brides? If not, it's a good idea to ask to see some as you need to see what her style of working is. Florists are like artists in a way, we all have our own style of working. Some florists still work in the traditional, heavy wired look whilst others work in a more modern look with a natural finish. I'd also advise going to see another couple of florists so you can compare prices, styles of working and whether you actually "like" her. Your florists needs to grasp what your ideas are otherwise it'll be a struggle getting your flowers as you want them.
Pricewise, this depends really on what style you decide upon. There are lots of styles on my website (link below) to give you a few ideas to go on. These are all artificial flowers but the costs are not a million miles away unless you have flowers which are way out of season or more exotic blooms. Georgie of By George on here will also be able to help you. She specialises in fresh flowers for weddings and will be able to give you a more accurate figure for the different designs. Just shout if you need any more help.
www.rainbowweddingflowers.co.uk - Designer silk wedding flowers - bespoke service throughout the UK. email rainbowflowers@paulandbrenda.demon.co.uk 2012/2013 Brochure on request