Replacing LCD that is already attached to new frame?

So I've asked about replacing my cracked screen before here. I've done more research and searching into the possibilities of fixing the phone by myself. I still need a third opinion from ATT, however as I think that they can't help me (cheaply), my question is: are LCD screens that come pre-attached to a new frame easier and better for a replacement job? I only ask because it is cheaper than having it fixed by an outsider and seems legit. I don't know if anyone has tackled this kind of problem but if the only fix I need to do is tear down half my phone instead of all of it to replace the screen then I will do it. I would just like to look into the difficulty of this kind of fix as opposed to replacing just the LCD. Thanks for anyone's thoughts or comments.