you didn't put a link to the extact drive but I looked something up on newegg and read some of the product review OCZ esata 16g
I wasn't sure if that was the drive you were talking about or not.
it appears from these reviews that you have to power the drives from a USB connector and there seemed to be some contention as to wheter or not the drive would just use the USB conenctor or th eSATA connector for the data transfers.( since it can use either with the eSATA being faster )

I would be afraid that 4 of them would over power your USB power supply unless you have some type of external powered USB hub.

because of how it gets power, I would not suggest doing this.