Most of these family tree books are put out by the authors
without thought to profit. They just want to get the information
out there and maybe recoup some of their costs.

The name is a bit deceptive because their resources, both in Books/Magazines, and CD/DVD, covers every state in the Union, as well as Great Britain, Germany, other places in Europe, and elsewhere.

While open to the public, membership has its priviledges, including computer access, and access to Members Only parts of the website.

http://www.ancestry.co.uk has Scottish censuses etc

http://freebmd.rootsweb.com/ has birth marriage and death records from all over the UK

http://www.genesreunited.com/ is THE main UK contact site.
Free to join. Small charge to join and contact others.
70,000.000 names, nearly as many members!
You will be very likely to find somebody doing research on this family there!

http://www.scotlandspeople.gov.uk/ and

http://www.originsnetwork.com/SOWelcome.aspx

I found wills FROM THE 1600s for my Scottish ancestors through the first site. I don’t remember the cost, because it was several years ago, but it wasn’t outrageous.

They have birth, marriage, death, old parish registers, census records and wills and testaments. These are the official records, not compilations by others.

You will most certainly find your Scottish ancestors at these sites! Good luck with your research!

Before 1855 things get trickier. Records before that year are called Old Parish Records (OPR). The General Register Office for Scotland does have copies of them, but they do not record every single person who ever lived. Also the details on the OPRs are sometimes sketchy. Searching on the internet becomes expensive when you don’t have complete details and you have to search through lots of possibilities.
The Mormons (The Church of Jesus Christ of Latter-day Saints) make some OPR information available at FamilySearch but, again, it is incomplete. It is, however, free to search.

An additional source of information is the nineteenth century censuses. Some census information is available for a fee at the General Register Office for Scotland. You can also purchase copies of census information from the Scottish Genealogy Society. There is currently a project underway called FreeCEN that aims to enter all 19th century census information into a free database. Volunteers are still working on the transcribing. The FreeCEN search engine allows you to search counties and parishes that have already been loaded into the database.

You may also be able to find church gravestones if you visit an area in person.

I think you’re missing one concept though: ‘mention’. Each historical record consists of mentions of people, relations, events, institutions. The genealogist identifies different mentions as belonging to the same entity. All the mentions combined form the body of knowledge about that entity. Mentions may corroborate each other or contradict each other, the latter needing further analysis to resolve.