Have found a company that does vinyl lettering
It seems to be intended for full size cars,boats,vans etc. but they appear to do any size/font/colour you could want.
I just bought two 30mm x 75mm sets of numbers for£6.55 incl. postage.Very easy to apply! Less ag. than transfers!
They are :www. vinyllettering
online ( I don't know how to make a link)