Yeah the price of strings is outrageous.
I shot an email to Bob Gollihur in the US, and he confirmed that if fitting Spiros to an NS, i need the S42 set which is 4/4
But i've decided against that now, as i was advised to go with strings designed for the NS NXT, which are the NS Contemparies , made by D'addario, ironically enough. Again, expensive, till i found the last set on Amazon for £80 - and snapped 'em up
Once fitted i'll be slinging the current thumpers in the FS forum
Good link too