How much would it cost to replace screen and battery for T mobile G1?

[JoyBJay]

I have had this type of phone for about two years, the phone is a little old but I love the settings color and size. Anyway I recently cracked my screen and shortly afterwards my battery began to give in. I would like to replace both tomorrow how much would It cost to do so, also would it be a better deal to go to a phone store that sales phones and repairs them or t- mobile itself. Which would be cheaper. Thank you