I note that prices of certain smartphones can go up and by as much as £50/80 on Amazon over a period of a few months. I would feel a little silly to purchase a smartphone only to find the price was £50 less the following week. Is there any particular time of the year when it is best to purchase a smartphone on Amazon.
Depends which make of smartphone you want. It is always best to buy when the latest model has been released - for example buy the 2nd generation of a phone just as the 3rd gen has been released.
The price of many things sold by Amazon can yo-yo alarmingly in just a few days. Have you used the Amazon price tracker, camelcamelcamel? Not only can you track the price history of anything, but you can set it to alert you when the price of an item drops to the price you are willing to pay.