Android devices running modern OS version on Jelly Bean or Kit Kat? Many new low-end devices are still shipping with Gingerbread. Gingerbread will be Google's Windows XP.
I don't know about other markets, but here, the majority of the absolutely cheapest Android phones (45€ inc. 23%VAT) run at least 4.1.2 and have 512MB of RAM.
I don't know how lower you can realistically go. Is a 128MB RAM really that much cheaper from a BOM cost perspective? Does it make sense for manufacturers to create a phone equipped with 128MB of RAM?
Also, while getting base FxOS running on 128MB of RAM looks neat this doesn't say much about how the phone actually works on the Web.
