[biophysboy]

The instruments do exactly as you say (run the sample N times), but this obviously comes at a cost. Also, keep in mind that sequencing needs to be very, very accurate to be useful. We share most of our DNA, and the small variations make up all the difference.

[nyolfen]

what cost do you mean? time/electricity? reagents? or the cost of someone else charging more for more reads?

[biophysboy]

Yes, those are all relevant costs. There's also a tradeoff between accuracy and the number of reads (how many sequences you can observe), or how much data you can get out of the machine.