Questions about adding a line

[miamary05]

Dropped/broke my iphone 4 today at work.. I've had the phone for about a year and stupidly forgot to add on insurance.. Been looking around to get the screen fixed and it could cost me up to 200 bucks.. What I would really like to do is get a new phone all together but can't afford to pay full price.. I'm almost tempted to switch carriers to get a new phone but I know that would mean I would have to pay the etf.. I've been reading the forums and some people say to add on a line and transfer it over to the main line and then put a "dummy" phone in its place and only have to pay a extra $10 bucks a month? I've been reading different scenarios all over this site and I'm just trying to figure out my options... Any help would be appreciated