> $120 phone at minimum
Uhh, no. I've paid $50 for this (non-contract):
http://www.gsmarena.com/zte_blade-3391.php
And that was new and in 2010. There are tons of amazing phones well below $70, in particular in "developing" markets (like India) where they get some exclusive low end phones that are a bargain for the spec.
If you go look on Airtel's website right now, go mobile offers, buy now, then uncheck the filter at the top and organise Low->High.
They have a 4.5" Android Quad Core, Lollipop phone for $87. If you can live with KitKat then they start at $31.95. If you want a "nice" Kitkat phone then $65.65 will buy you one.
So, yeah, $120 is nowhere ballpark near the minimum. The minimum in the literal sense is $10 and the minimum with Android is $28.81. And that's just buying directly from Airtel, new.