You can purchace the screen through apple and take it to a apple retail outlet and they will install it and the price for the screen with repair is 199$ + applicable tax
Apple will not do this. Please refrain from spreading misinformation.
Apple does not sell parts.
Apple does not replace screens... they may replace the back glass on the 4/4S and they will replace the battery, but that is it.
Apple will provide an Out of Warranty replacement for the appropriate price based on model, for the 4S it is $199.