You cant build your own laptop. Parts too rare, assembly too dificult.
below 1000$ no SSD
Asus-Lenovo-Sony <- make good laptops
Acer - HP
Had no run-ins with Dell so far. Avoid macs too overpriced.
Things to look for first:
Good Screen, meaning it doesnt fade or lose collors when looked at an angle. Has Black Blacks(not whitish grey) Has bright whites. Also if you can: avoid 1366x768 most crappy screens come in this format.
If you tend to play minecraft and games UP to league of legends, Stay with HD 4000.
if you want to play CoD, BF3, Skyrim, Crysis or something in that caliber get a Discrete GPU, Nvidia is prefered in laptops.