Cost of changing a battery for iPhone 5S?

My iPhone 5S battery is not doing so well. I've been told after a check that it will probably have to be changed.
In the store I got it checked at they told me the price of changing the battery would be about 120 pounds, but that they often instead of fixing the battery would "swap" the phone for a brand new one, which would then cost about 250 pounds.
After a quick internet search I found that many places offer to change the battery for about 40 pounds.
Is the store I went to just overcharging or are these cheaper places not to be trusted?

What happens when I reset my IPhone 4?

After resetting my iPhone what do I loose? Will I be able to download my music without having to purchase it again? Including games? Do all my photos delete? Where does my iTunes money go? How about contacts etc. I just need a list of what is lost, and how to retrieve it again if I'd like certain things back without spending money again. Does this make sense?

How to make funny edits on Vine?

Like you know "mason, chill out!" and "no chill will" or "ImBlueWhoYou" on Vine? Well I was wondering what editing software they used. I know some basic editing but only use free apps on iphone 4 ;D so I was wondering how to make better oness.

Why is camera not working on iphone?

I don't know why my camera is not working, I'm sure it is a software problem, it just shows a black page. All features are working but it doesn't show anything. It is not working on other apps, like Instagraml. The front camera is not working. How can I solve this problem?