In my opinion, expensive laptops are a waste of money. Everything is on the board, so besides RAM and HDD there is no upgrade path.
Since you seem determined to get a laptop though, I'll give some pointers:
- Laptop GPU's are typically dumbed-down versions of their Desktop counter-parts. Make sure its actually good enough to do X (use online benchmarks, making sure you have the "M" or Mobile version).
- Test it at a local store if possible. You can order it online once your done, but its best to test that it feels right before getting it. Also, keyboards that feel cheap typically are, get ready to order replacements (my last laptop I used ~6 keyboard but I do a bit of typing).
- Make sure the brand has decent support. It might be cheaper in the beginning, but when shit breaks its nice to be able to just send it in instead of pulling hair out. See how their customer support ranks, remember you're not only buying hardware but a warranty/support too.
I might of missed a few things but these are the big ones in my opinion. Specs are good, but there is more than high specs.