I work on a research ship and my phone (aka alarm clock) - which has had a hard life of water and welding related accidents - stopped functioning completely. Home button, speaker and charging functions all dead or malfunctioning...
iFIxit overnighted the parts and tools, and along with the excellent guides, my phone is working again! :) New screen, new dock connector, new home button, new battery, it's like a new phone!
Just do it! It's not that hard. Oh, and if you forget to order the magnetic screw tray, get a piece of paper and tape down each screw as you take it out and label it. would have been a real mess otherwise.
SIM Card Eject Tool
P2 Pentalobe Screwdriver iPhone
Pro Tech Toolkit
iPhone 4 Replacement Battery
iPhone 4 and 4S Speaker Enclosure
iPhone 4 Home Button Assembly