When it comes to Valentine's Day flowers or anniversary flowers, you can't go wrong with giving a traditional arrangement of a dozen red roses accented with baby's breath (gypsophilia). The following video gives step by step instructions on how to arrange a dozen roses in a vase.
This video uses red freedom roses, gypsophilia, tree fern (Asparagus), and leather leaf (Rumohra). You can obtain these supplies at your local florist. Grocery stores often have great floral departments where you can also buy these supplies individually.
The cheapest place to buy a glass floral vase is at a thrift store. If you can't find what you're looking for there, try the floral department at your local grocery store, they usually have the best selection this time of year. Another way to obtain nice floral vases is to order flowers online, and include a vase in your order or go to your local florist. Of course, if you have an account with a flower wholesaler, you can also get great deals on vases from them as well.
Proflowers.com often offers a free vase with your order:
FREE vase with your flower purchase. Gifts starting at 19.99!
finally has some halloween arrangements. Proflower mostly just has arrangements with fall colored flowers. Lots of beautiful bright oranges and deep reds. 
Its the only site I've seen with Orange Tulips. If you are looking to give more than flowers, they also have a variety of gift options, including a variety of fall treats and cookie bouquets.
also has a large variety of fall floral designs. They mostly do flowers, there is only one treat gift basket here. They offer several vase and container arrangements. Some of their unique items include arrangements in a class cube and a ceramic pumpkin. They also have several arrangements using sunflowers.
offers many basket arrangments and centerpieces as well. They do not have any Halloween arrangmets specifically though. Most of their arrangments use yellow flowers, in addition to reds and oranges. Floral arrangments in baskets are great for displaying at an office, and they can last a long time if you continue to water them, floral foam needs watered added to it. Sometimes baskets or containers are more advantageous because you don't see they water get dirty when you don't clean it out. They have over eight pages of "Fall" arrangements, so check it out if you can't find what your looking for at Proflower or USAflorals.
