Hello friend. I noticed the comment about the many used garett at pro's for sale. Personally sometimes it spooks me just like the "White's Bullseye" pin pointer which I have seen many and at lowered prices. (Kinda like the stocks, when a bad investment they drop and people run away and sell off.) Thanks to the high tech we have and great comments/experience from our "Think Tanks", I learned the buttons fail on many bullseye units and did not take the wear & tear on the field. I have seen posts and their exposure hoped they fixed their problems but the work great when operational. I am not trying to put down any companys, they are in business because the many products do work well. I was looking at the Minelab but the best is out of my spending range and one youtube said a famous trails (sold at Radio shack) & the cheepest Tesoro works as well as the low priced Minelab and you could buy 2 metal detectors for the same price as the one Minelab. (Check the youtube.)
Now I have not had a Tesoro Cortez, but let me say this. I have one of the first made original-production classic 1980's Tesoro Golden Sabre. I scored on ebay, 31 years old, still operational. I use it in all metal mode & discriminate & at the nickle setting.Sensitivty set at 3-4. I dig all targets so I do not miss nuggets, coins and artifacts. (I do get alot of junk wire & 100 year old "Square Nails" from the 1800's but that is part of the game.)Not being the original owner I phoned the Tesoro Company, they gave me settings-advice and offered to give it a quality control check-up! They even mailed me (FREE!) a battery holder (which was missing) and a new battery cover with the "quick pull" plastic pin/gromet. Excellent Customer service.
We all have our own tastes, I go on youtube and see people in the field. (Some I think salt their finds to make it look easy or they are lucky each time they go out but I check out their technique and I am happy for all who really do find it for real. Good luck friend.