Considering replacing my desktop

[Bicko]

Hey all, I'm currently considering replacing my desktop computer (and ancient laptop) in order to get a decent laptop that'll still let me play games at least as well as I can now (or better) and also do work (games development) when I'm on the move.

I'm curious as to what laptops are available/recommended based on my spec, and how much they'll cost. My current PC specs are:

• Intel Core i5-2300 CPU @ 2.8GHz
• AMD Radeon HD 5700 (768MB)
• Crucial Ballistix Sport 8GB (2x4GB) DDR3
• Asus P8Z68-V LX Motherboard

Out of interest, would anyone have a rough estimate of what these components would sell for second hand? I'm also using a Lian Li PC-A05 case, if that's worth anything these days.