Country Living Magazine has a good article on growing amaryllis this month and these should be planted in the next week or so if you want them to bloom around Christmastime. The bulbs should be planted in a pot which is only about 1" wider than the bulbs as they flower best if they are crowded in - if you are going for a spectacular multi-bulb display it is worth starting the bulbs off in seperate pots and then packing them into your chosen container when they are about to flower. This also allows you to chose ones which will flower at the same time.
Amaryllis can also be grown in water like hyacinths, though this is much more of a strain for the bulbs and they will not survive to flower next year. Put the bulbs on top of a suitable container, a large jam jar or small kilner jar works - what you need in something that will keep the main part of the bulb out of the water but allows the roots to access water. A pinch of charcoal will keep the water sweet and then in it just a case of topping the water up as the bulb grows. There is no need to keep Amaryllis in the cold or dark.
The main challenge is working out a way of keeping the flower from falling over. In a book I have recently bought, Forcing etc. by Katherine Whiteside, there are beautiful photographs of Amaryllis growing in water soaked gravel at the base of a tall glass straightsided vase - the vase keeps the flower stem from toppling and the gravel acts as ballast. This is how I am going to grow my amaryllis this year.
I have some Amaryllis bulbs for sale as bulbs this year - Appleblossom (pink and white); Ludwig's Dazzler (white); Liberty (Red) are £3.75 each for size 34 which should give at least 2 stems with 3-4 flowers on each. I also have a very dark red called Royal Velvet which is £5.50 for a size 34. If you are after something even larger I have a limited number of size 40 Red Lion bulbs which cost £5.50.
For comparison the bulbs that you tend to get in the gift boxes are size 28.