Scotland's People is pretty good for information before the Statutory registers came into play. It's still good for basic information afterwards.
All you need is to be a registered user, which is free.
The costs involved come if you want to buy the record (handily given in pdf format, immediately downloadable).
SOME of what SP offers can also be found on FamilySearch, or ancestry (including using library edition). Unfortunately, some of those are just transcriptions, not actual images of the documents.