"Efficient" and "create from scratch" are polar opposites in this case. The efficient way to get parcel data is to get it from someone who already has it. In the US, it's typically available on a county-by-county basis, often from county tax auditors.
For example, the parcel shapefile for Summit County, OH is a 65.5 MB download. It's also available as a spreadsheet or KML. Or you can access this county's parcel data without downloading it by connecting to their web feature service. Other counties may not have such conveniently accessible data. In some cases you may have to contact the county auditor and request the data be sent to you.
Each county's parcel data will be on the order of 10-100 MB, so nation-wide coverage would take a long time to download and take up a lot of storage space. That's why anyone is willing to pay for services like the ones you mentioned.