Scotland is, as far as I know, the only area which does uncertified certificates, and then only for events before certain dates (100 years ago for births).
There is a push from genealogists to get this facility for the rest of us, but until then we usually have to cough up the full amount.
Remember that BMDs can be ordered from the local offices as well as the GRO. This means you often get a copy of the original registry entry, rather than a copy of the transcript sent off to the GRO by the local Registrar. We all know how often errors are made in transcriptions! The downside is that local offices are allowed to charge more than the GRO, and, local government finances being what they are, they do.
If a marriage took place in a Church of England church, then the original register may have been deposited at the relevant county archives. All registers over 100 years old are supposed to be placed thus for safe keeping, but there are always clergymen who hoard, often charging fees for access.