the age old problem rears its ugly head again

do you offer monthly or two monthly from the start?
if not i think it puts you on the back foot especially in a situation like this
has of last week i had a price menu laminated detailing house type,no of beds then two coloums one for monthly and one for two monhly so lets say the following
semi detached £10.00 (monthly) £15.00 (bi-monthly)
detached (3/4 bed) £12.00 £16.00
blah blah and so on and so on
conny £3.00 extra
prices assuming no large areas of glass etc
and that way i show it to them let them choose no surprises hopefully
or you can switch it to two months and do half a job?