But, but, but, mass producing them will be cheaper! *grin*
Seriously though, buying 50 of the same resistor is cheaper (as a single unit) ... I have yet to buy less than 100 when it comes to stuff like that. I'll always find a use for them in whatever future project I come up with.
In your case, if you don't foresee having a use for them in the future, then yeah, buying them in small quantities will be the way to go.