Recommend me a metal/plastic shed

[Dr_Gonzo]

I'm looking to put a decent sized metal or plastic shed in my back garden. I'm looking for something sized roughly 6ft high, 6 ft deep, and 8 ft wide. My budget is around £500. I'm not sure which material is best although I've heard that plastic ones are generally better.

Also, when it comes to installing it, what sort of foundations are required?

Thanks in advance,

The Doctor