I did my own. We had loads of flowers, we had:
Bridal Bouquet
Bridesmaid's Bouquet
Mother of the bride gift bouquet
Three flower girl flower wands
1 wrist corsage
2 women's buttonholes
3 men's buttonholes
2 boys buttonholes
14 sets of table decorations for food tables (each had 3 proteas, 6 roses and a number of other flowers too)
3 sets of table decorations for the register signing table, cake table etc
Choosing flowers can rely on what's in season. Ours included proteas from South Africa and lots of roses, as well as tulips, gerbera, gypsophilia and fillers. The Proteas were expensive, had I gone without those the price would have been about half what we paid. If I'd gone for something cheaper than roses I could have brought the price down even more. As it was we spent £800, but as I said,could have brought it down to about £3-400 with different flower choices. It took us a full day to put all of the arrangements together because we were doing so many, but they were utterly stunning when done. I had tonnes of compliments and was asked several times who did the flowers. I've never arranged flowers before, so if I can pull that off anyone can!
A few tips for you:
There are tonnes of tutorials online, on how to put together bouquets, fix buttonholes etc, as well as how to preserve flowers to keep them looking their best all day.
You need to take into account things like ribbon and wire in your costs, not just the flowers. You also need to remember any filling, or greenery you need, and equipment like sharp seceters/scissors, to trim stems, and a cool place to work, where you can keep the stems in buckets until you're ready for them, as well as somewhere to store them when done.
You also need to take into account time in your planning in the run up to the day. Flowers need a day or two to condition after delivery from the wholesaler, if you order from them, but need to be as fresh as possible to look their best for the big day, so would need to be delivered 2-3 days before, and put together the day before your wedding. In the meantime they need to be stored in water somewhere cool.
Putting together bouquets can be hard on a manicure too, so schedule accordingly, or remember gloves.
Keeping to what's in season, or what's in the supermarket or your local florist will bring the cost down too.
Work out a basic bouquet design, and that will tell you how many of each kind of flower you will need. If you're ordering from a wholesaler I would add about 10% onto whatever number you think you need, just to cover broken stems, mistakes etc.
I would go for it, do som research on where you can get the flowers you want, we used Triangle Nurseries, but like I said, a supermarket or florist might work out well for you. Good luck :)