I like making cables and as long as you use a basic cable tester to ensure all pins on each end are passing electrical signals there is NO difference between store bought and hand-made. I've never run into any issue where there was a break in the middle and this can happen to any cable--store bought or not.
The big cost is time and I know most of us would prefer to NOT waste time doing these sorts of tasks. We are in the process of re-cabling our racks due to the previous admins being lazy about the lengths of cables they use (i.e. 50 foot cable for a 7 foot run) with APC patch panels and simply bought 1ft, 3ft, 5ft, & 7ft lengths of the snagless type...they work fine and save us time in this very time-consuming project. If we need a special length we will make one....for many cables...buy them...
good luck all...