ATC VS. Gri Gri
Price wise, the ATC definitely wins. It costs about 1/5 of the cost of a gri gri. Gri gri's costs about 100 dollars in general. For example:
http://www.amazon.com/Petzl-Grigri-Belay-Device-Blue/dp/B007MQSUQG/ref=sr_1_1?ie=UTF8&qid=1394904527&sr=8-1&keywords=grigri
ATCs on the other hand costs less than 20 dollars! For example:
http://www.amazon.com/Black-Diamond-Belay-Device-Platinum/dp/B004GY9SYU/ref=sr_1_1?ie=UTF8&qid=1394904579&sr=8-1&keywords=ATC+climbing
So obviously I got my first ATC on amazon! :) I'm not a fan of spending extra when the other works just as fine and you practice the same technique.
The black diamond ATC
As you can see it has a nice chrome mocha colored finish with a black loop at the end. It has two holes for ropes to go into. Cheap and good. I definitely recommend this!
Locking Carabiners
Some pictures for you to compare the carabiner with an autolock system and the carabiner i bought with a screw gate.