Sometimes I find the cheapies aren't as obvious, you stare at them and try to figure out if one line is darker.. Ugh.
So I use Internet cheapies in general, and then if it looks dark, I use digitals to confirm if the cheapies were actually positive.
Then a pack of expensive digital ones lasts me several months.
Hey, you didn't like my idea?!?! Kidding! Hehe. I did that for a while too, then just totally ditched the digi's. Good luck, whatever you decide.