If you did fry the SLA7078M it's going to cost better than $10 to replace.
Find SLA7078M Stock and Compare Prices Across the Most Reputable Distributors in the Industry.
A Linistepper driver would have cost you a bit more, (or less if you made it yourself) and would cost about $5 to replace the drivers if you fried them. It would easily handle that motor.
James hosts the single best wiki page about steppers for CNC hobbyists on the net:
http://www.piclist.com/techref/io/steppers.htm Disagree? Tell him what's missing! ,o)