Theres nothing to buy except the collection of electronics. Companies get bought because they have value. Value in future sales, value in intellectual property (patents) and value in the name.
Tesoro hadnt produced new technology or designs in a VERY long time. Why would a company buy outdated tech? Tesoro had very few sales. they tried to survive on the past reputation. There are people who loved the brand and the detectors, but typically those customers are old customers who have been using Tesoro for many years. You cant bring new customers with outdated decades old tech.