Well then, make a top 3 list of what is the most important for your laptop based around what you plan to use it for. Battery life, weight, portability, durability, and price are some considerations. Mostly, it depends what you plan to do with the laptop... ie gaming, lots of typing, rendering, a general jack-of-all-trades, or something that doesn't need a wall outlet every few hours....
Building your own laptop is not something I (Nor I think anyone else here) recommends... you will pay more to build your own laptop than what you can get off the shelf. Cheap notebooks tend to sacrifice durability and will feel cheap, many will have plenty of flex in their chassis/frames or minimal display protection which is bad. Lower end hardware is obvious, but things like a celeron processor also tend to have more power consumption than higher-end and much faster processors. They also tend to have slower 5400 or 4200RPM drives... a desktop drive rotates at 7200RPM, and the performance difference is very palatable to the user.