I've used one of these:
http://www.glock.com/english/outdoor_entrench.htm
for about 16 years, well, I've owned one that long anyway. I stopped using it about 5 years ago, at least for it's true intended purpose.
If you need to dig deep holes in a hurry, go for something much heavier, the issue folder ( UK issue) is okay but I've seen them destroyed by ham fisted squaddies once or twice, and they are quite a lump of steel to hump about.
DONT buy a cheap copy; they fall to bits.
The Glock is nice and light but actually, very strong. It has a tendency to flex a bit, as the handle is made from some sort of polythene type plastic but its not a major issue if you take your time.
A bonus is the heavy saw blade, stored inside the handle, ideal for cutting through roots in the side of trenches or just 'holes'. Of course; you can also cut wood with it if you want
Not sure of the price of them these days mind
atb
R.B.