Provided the modular connector from the PSU is somewhat standard (I've never seen one with modular SATA, so I honestly don't know), you could always buy the connectors/pins separately and make your own:SATA Connectors
and pinsMy guess for the modular end of the cables would be one of these
With that end on the PSU, if you truly wanted to do this you could cut one of the ends off a few inches from the connector and splice/solder the new wire onto the older wire.
Some 18 AWG stranded wire
Even with shipping they'd be cheap, you could get them the exact length/configuration you need, and you'd save enough to get sleeving for them as well.
There are some other options as well:
You could get pre-made extensions
There's also these
that are 4-pin Molex to SATA, probably not what you want, though.Edited by liquidzoo - 3/20/12 at 12:05pm