Obviously UK NHS prescriptions are fixed price so the below is for private prescriptions being fulfilled in UK. (All prices in British Pounds £ (current exchange rate to USD is £1 = $1.2))
Rapamune is charged at £25 per 1mg (wholesale price) plus the pharmacy mark up which can be as much as 50%.
Generic Sirolimus is £3.25 per 1mg plus the pharmacy mark up. (Tesco supermarket have much lower mark ups than the local pharmacy and quoted me £110 for 30mg of Sirolimus).
My local pharmacy could only source Rapamune and not Sirolimus as they only use one wholesaler hence best to go to the big chain-stores.
(Obviously better still if one could persuade an NHS doctor to prescribe it)