Yes you can use laptop cells, such as Tesla does. You will have to take apart the packs and re-weld them into a pack that will work for you. To manage a great number of cells such as you would need for a car pack you will find it a hassle yes.
Main cost is tools and time to test cells. Access to a large amount of used battery's is key. Lots of people recycle and use cells from power tools. These tend to allow a higher C rate than a laptop cell.
Main cost is tools and time to test cells. Access to a large amount of used battery's is key. Lots of people recycle and use cells from power tools. These tend to allow a higher C rate than a laptop cell.