With android phones going into the sub 50$ price range (Crappy experience, obviously), WP could really attack here. We could push the specs down more, and still have a good experience. WP is a very optimized OS that can run smoothly on 256-Mb single core devices. So let's make one.
LUMIA 420
-512 MB RAM
-4GB HDD (Assuming it has GDR2, so other storage issue would be gone)
-WP8 GDR2
-Single Core 1GHZ Processor
-$79.99 or 69.99
LUMIA 320
-256 MB HDD
-4GB HDD
-Single core processor, if WP runs on less then a 1GHZ processor, let's do it.
-WP 7.8 or 8.0 GDR2, if 8.0 is stable on these specs, then use WP8.
-$49.99 (Or less/more until the OS is stable at the min specs)
LUMIA 420
-512 MB RAM
-4GB HDD (Assuming it has GDR2, so other storage issue would be gone)
-WP8 GDR2
-Single Core 1GHZ Processor
-$79.99 or 69.99
LUMIA 320
-256 MB HDD
-4GB HDD
-Single core processor, if WP runs on less then a 1GHZ processor, let's do it.
-WP 7.8 or 8.0 GDR2, if 8.0 is stable on these specs, then use WP8.
-$49.99 (Or less/more until the OS is stable at the min specs)