Undoubtably the Lesche is the premium digging tool (and I may well order one sooner or later) but for those who want to save $$$ or dont want to wait for their order to arrive, I have found a couple alternatives that work quite nicely.
One is a paint scraper that I got from Dollars n' Sense for $2.50. It has a chiselled edge and has a bit of flex meaning it wont snap easily. I find it's really good at cutting a plug and then you can lever it out with a screw driver. I'm sure you can find even better ones at a hardware store.
The second is the widest, strongest chisel I could find at bunnings. It is 38mm wide, strong, sharp and heavy. I only used it this morning but found it a terrific plugging tool. Cost me about $23. Naturally the sharp edge will get roughed up over time but I'm thinking it can go the distance.
So before you rush out for the Lesche you may already have something in your toolbox that will do a decent job.
I have broken three different brands of trowel/hand spades, they are nearly all crap at being used to lever soil of any substantial weight. They bend and eventually snap.