First, I know people who bought a Lifetime Warranty Bounty Hunter, D-Tex, or other detector make that came with such an offer. They are no longer covered because the companies, like Bounty Hunter, sold, or all the others who made such a warranty claim simply died.
Also, through the years I have seen more turn-on-and-go Tesoro's, having the internal preset GB, need to be 'serviced' which usually just means recalibrating the internal GB trimmer so it worked with each of the search coils the person owned. If you have a Tesoro with manual GB, then there's no problem, and other than those service needs, I don't think that many Tesoro's really end up needing service all that often.
Thus, the money saved by buying a new or virtually new detector more than off-sets any repair cost, IF one should be necessary.
I have purchased a lot of used Tesoro models, through the years, or traded for a Tesoro, and I have only had two problems and both were easily fixed w/o factory involvement. Tesoro detectors were built well enough that if you have a model without a design glitch, and if it has manual GB, you really don't need the warranty.
Therefore, you ought to consider a good, clean, 'as new' used Tesoro and save $$$. Buy my as new Outlaw and you'll find out.
A well built and good working Tesoro that ought to outlast the Tesoro company and keep right on working.
Monte