Costco have books of stamps, with about an 8% discount, working out to just under 43p per first class stamp, when the rise to 60p in a few weeks is taken into account, this will represent a return of nearly 40% - easily beating any other return on savings etc.
I have stocked up with a couple of hundred (I work from home so use a lot anyway) and for me this will save me a lot over the next few months.
I know this is not for everyone as membership is required, but for those able to access it is a good oppertunity.
Other retailers who were discounting such as superdrug have been limiting purchases, and now appear to be running out of stocks, Costco seem to have large supplies.
They also have 2nd's and large stamps at similar discounts