i am running vista 32bit homebasic oem , is it possible to change (legal ways only please) this to the 64bit version without buying the os again ?

I dont think the anytime upgrade will swap 32 to 64 bit, so probably have to buy it again

was told about the below url , bit it says no offer found

http://www.microsoft.com/windowsvista/2057/ordermedia/default.mspx

if i was to buy it again where would be the cheapest place ?

Probably worth buying Windows 7 OEM instead.  

i have 60 quid spare atm , this is not enough lol

That said.....
http://www.tomsguide.com/us/64bit-win7-upgrade,review-1496.html

problem with that is no body in my local area i know has vista 64bit , and i have not found a legal place to get it either lol

If you have a friend who is a student, you likely can get a student deal on Win 7 making the home version <£50.

In order to go from a 32-bit os to a 64-bit one, you will need to do a complete re-install from scratch.

pidgen.dll is the same across both versions. Therefore, the key you used to install 32 bit will also work on the 64 bit version - you just need the 64 bit media.

Aquire it from somewhere and I can confirm the MD5 hash for you so you know if youve got some spyware ridden version or not.