the LBS will attempt to charge you almost as much for the threading service (on a full set of spokes) as one of these would set you back...
http://www.ebay.com.au/itm/NIB-HOZAN-C-700-Spoke-Threaded-Device-Threading-Machine-New-/111556156131?pt=LH_DefaultDomain_0&hash=item19f943dae3
you also need the larger size die, which are also expensive but... they expand, but only slightly.
from then on you can cut your own spokes, friends spokes, never worry about spokes ever again...
also, hunt around. i got mine for $127 (which would be about $110 for you in the US)
no, a standard tap and die set wont work. those smaller(cheap...what you want would cost twice the amount of one of those kits...for just one!) taps are badly made and will just cause your spleen to burst... especially if you got stainless spokes! (i cut all external stainless threads on a lathe cus i havent found a die that will start on the stuff yet! i dont use cheap dies, either
)
also note the die used on the real threaders. its a ROLLED thread...
one...the thread is stronger as its forged rather than cut.
the spoke is stronger as a stud/thread is only as strong as its root or small diameter. by cutting material away its reduced in size. ie,if you CUT your threads...youll end up with 12 or 13g spokes despite the majority of the spoke being 11's! sorta defeats the purpose, yes?
the rolled thread allows the spoke nipple to go PAST the thread if necessary.
those weird bolts you find with washers on them and the thread prevents it from sliding off? rolled
as most high tensile bolts are.
also, not a bad idea to do what crassius suggests, change the lace pattern. or at least, double check all your measurements and recalculate!
http://www.bikeschool.com/tools/spoke-length-calculator