Why do people pay so much more for iPhones on eBay?

I was looking to buy a 32g iPhone 5 on eBay, and saw that some (that ended today) sold for about $900 (locked on AT&T)! You can buy this same phone without contract for only $650 on Apple's website. What is the meaning of this?

Added (1). @Mark read more carefully… You can buy them on Apple's website… This has nothing to do with supply and demand.

My New iPhone 4 won't send or receive text messages?

I have checked the service centre number which is correct, I have updated the ios software thing (I'm not too clever with Apple products but yes it's been updated).It says iMessage is waiting for activation but it has said this for ages now. I have tried absolutely everything with still nothing. I can make calls, use the internet, I can do everything else! I just can't send or receive text messages… Will someone please help me?

Are there any personalized news sites?

Such as apps for mac or iphone, even websites? That I can personalize to show news from several different areas all into one? I'm most interested in health/fitness news and maybe local/national as well. I'm just looking for brief things that I can read to know what's going on in the world… It doesn't need to be long or specific.

Is Shopping.com Reliable site?

I was searching for Iphone on Shopping.com but i surprised with Big Discounted prices (about 60% or more). Are those devices have some kind of faults or the are working well?

Iphone 5, which carrier with?

I live in London and my blackberry contract with vodafone is coming to an end. I have already decided that I'm going to buy an unlocked iPhone 5 and then buy a pay monthly sim card (30 day rolling contract/12months) However I'm indecisive of which carrier to use. Vodafone for me is out of the question as
a) it is ridiculously overpriced
b) i have had problems with them overcharging me in the past, claiming I did 200 texts in 1 day!
c) i use it also in my school and there's rubbish coverage around there and also the rest of edgware!
I'm currently stuck between 4 carriers. Giffgaff, T-Mobile, Virgin Mobile and Three.
I'm looking for quite a lot of data in my plan and it should preferably have unlimited data and quite a lot of texts. For those reasons I'm leaning towards giffgaff and 3 as they have the best deals for internet usage. However I'm not sure how reliable these 2 companies are and if they have high data speeds considering I would use it mainly in London. Please tell me any personal experience you may have or know about including how reliable the company is, their coverage speeds around London (indoors mostly as well as outdoors) and also which have the best deals.

Why does my iPhone 4S die when my battery is full?

I recently got a used iPhone 4S and the battery is terrible. My battery can be at 100% and ill take a picture and it'll die. I can't use my phone for more than 30 minutes at a time. I've even had to buy a portable charger and it will still die. It's dies randomly all of the time even if my battery is full. What should I do? What's the problem?

IPhone 4S back plate won't slide off?

I dropped my white iPhone 4S (At&T) about a week ago and ordered a replacement screen and the appropriate screwdriver so I could fix it myself. I got the bottom screws out from the bottom but the back plate won't slide off as all the forums I have looked at says it should. I'm slightly pushing up toward the top of the phone but its not budging. The only thing I could think of is maybe its jammed from when I dropped it? Would wearing gloves help to give me a better grip?

Any help would be greatly appreciated!

Added (1). Got it to come off. Your right apple doesn't want you to take it off which is why they have special pentalobe screws… Just took a little budging and it came off.