Implementing Option-only Pricing in Drupal Commerce (D7)
Drupal Commerce can be confusing to get one's arms around, even if (or especially if) coming from using Ubercart or some other relatively point-and-click cart. I recently had the need to do something I considered a simple requirement, and having retail experience, something intrinsic to most catalogs: products with option-only pricing.
A project manager walks into a bar after a long day and orders a drink. While enjoying it his cellphone rings and he answers it even though it's his wife.
"Where are you?" she asks.
"At the pub," he answers.
"Are you almost done?"
The PM looks at his drink and ponders for a moment.