Did you view the links I gave you? I found an OEM Glass, LCD, Home Button, Speaker assembly for only $115 on eBay.
It's a quick job with almost 0% chance of breaking anything. It's like changing RAM in a computer. Snap off... snap on. Done.
Also, the assembly comes with all the tools.
You seriously can't compare this to changing RAM? When pulling the iPhone apart there is a very real chance of breaking a connector if you're not careful and the two pieces come apart too quickly.