How big of an upgrade would it be from a iPhone 4S and a 5C?

I have no problems with my 4S except for the battery life, I would be ok with getting the 5C over the 5S because I don't want to drop $200 on a phone. I know the 5C is definitely upgraded over the 4S, is the $99 cost justified and it would be worth buying it to replace my 4S or should I wait until the 5S drops in price?

You can compare the 4s and 5s and 5c on the apple website
AND
You can SELL your 4s for $100-$200, so it is kind of a wash.

I would go with the 5S, the 5C is slower.

5S will not be $99 for 2 years. 5C is a good upgrade, larger screen, bigger battery, better camera, etc. Unless you only make phone calls, the upgrade is worth it.