Hey, I'm glad you're liking the WP. Honestly, I think WP should be great. That said....
Android phones are starting to get into this territory too. OnePlus 2 is $400. That is 4x the cost of your $100. But it is less than half the cost of my $1000 Note 2. (I don't buy on contract because I have a grandfather plan on VZ for unlimited data). My wife's phone was $700. Next refresh in about 2 years we'll be in the OnePlus store.
The reason I say all of this is that we should all, across every platform but Apple, be looking forward to getting less expensive, higher quality devices.