I think online certificates from the GRO
http://www.gro.gov.uk/gro/content/certificates/are cheaper if you have the GRO reference. You do not have to give the names of both parties if you have this reference. You will need to create an account, certificates are £9.25 each.
As Carole suggests, a search on freebmd may give you the spouses' maiden names for free without a certificate [which are very useful for confirming the names of the fathers of each party] if you know the forename.
I suggest for each search you specify;
[1] the likely area of the marriage [county or town] which you say you know
[2] the relevant brother's name [and spouse's forename if you know it]
[3] a span of years to search depending on the brother's year of birth - I suggest 10 years either side of age 30.
On freebmd marriages before 1912 will usually give you 4 names if you click on the page number, hopefully 2 males & 2 females. If you do not know the brides' forenames you will have to order the certificate with the GRO reference & the male's full name. Again, as Carole says, after 1912 you get the surname anyway.
Josey