Flexible Couplers on Retrofit?

I am in the process of putting together a CNC retrofit Mill using a
Xylotex controller and NEMA 23 116 oz./in steppers from Jeff. I am
putting this on the $279 s axis machine that Central makes/sells. I
know for this price it can't be the best in the world but I am not
looking for that right now. I figure I am going to have just over
$500 into the entire setup when I am done. Get what yo pay for I
guess.

Will I need flexible couplers from the steppers to the screw? I was
looking at flex couplers and they are about $20 a pop for the ones I
found. Is it an absolute neccesity to have flex couplers or can I
make my own solid coupler? I realize there are factors to consider
that would determine the neccesity of flex but I guess what I am
asking is if there is any chance to make it work without them?

Any good sources for cheap flex couplers or a way to fabricate one?
(links)

Thanks a million Guys and Gals!

Todd (RiffRaff) Meidinger