G.D.
You can find them anywhere. The problem is that you have no idea if it will work again. I have been a colorist for 10+ years and have to admit, I have seen some nice hilites come outta boxes, but its kind of a chance you will have to take and hope it works out or you are looking at having it professionally corrected for a significant amount of money.
I am offering 20% off my services in the month of July if you happen to be near Vadnais Heights. Its a bit pricier but you know what you are going to get in the end.
Good luck and if you have any questions, contact me.
Gabby @ Hair Matters ###-###-####