So, you buy the cheap battery, the genuine cells, then you disassemble the cheap battery, reassemble it using the superior cells and then you also hack the firmware of either the battery or your laptop so it can still be charged.

Even just looking at the parts cost, are you sure you would still save money compared to going with the original battery? And of course you have to add your own time to this (if you actually like doing this, then it'll be cheap I guess) and the value of the warranty that you certainly will have voided at that point.

I totally understand that this might be a fun project to do and it will certainly be a nice achievement when you're through, but can this really be rationalised with cost of the original part?