It will probably be around $150. The back glass is probably $35 but not the front. The phone needs to be pretty much totally taken apart.
I see it can be done locally here for $70 by a third party.
If you look on youtube you'll see it's quit a project to DIY. DIY will void the warranty too, I don't know if a third party doing it will, probably so though.
I read where if you ask really nice they may sell you AppleCare+ for $99, then use one of two instances of the $49 fix, leaving you with one $49 fix left, and costing $149 total.