Honestly - with the cost of most laptop motherboards - you'd be better off buying a new laptop. Laptop components are made specific - so you need the EXACT motherboard that will fit into your laptop. They're not like desktops at all. There's no standard. And those specific motherboards that fit into your laptop? They're usually only $100+ cheaper than the whole laptop.
If you're looking to put together something on a budget that you can upgrade later, go desktop.
Concur, financial resources permitting..
It's time that we all acknowledge that laptops are throwaway computers, not intended to be anything other than the precursor of future models. So many new models come out each week/month...that the manufacturers have ceased to even provide support data for models which previously would have remained on file forever.\
I'm not a "tech" of any sort, so the idea of taking a laptop apart is just too much work for so little return in my world.