The GRO has provided a facility to search the BMD indexes online without charge.
They are also running a trial to provide certificate details as pdf files for a reduced fee of £6.00. The full certificate can still be ordered for the standard charge of £9.25.
This is a short term trial running until 30th November or when 45,000 certificates have been issues.
Details and registration can found at the GRO web site here.