Why is the iphone 4s only available in 8g? Is it worth it

I have to buy a phone now as mine is broken and my parents won't pay it. I'm not old enough enough for a contract and was thinkoing of the iPhone 4s. On the Apple store it's £349 but can only be purchased as 8g.

Is 8g worth it? It's a lot of money to spend on a phone and I can't really spend any more. Incontinence trust second hand phones as they may not work etc.

Is it value for money or shoulld I look for another phone?

Because old yeller had a roid rage.