I have used various broadhead targets and pretty much been disappointed with all of them.  Any suggestion?

Dirt. Sand. A creek bank or bed.

What Ben said

Big red Simpson Desert sand dunes or sand drifts around small spinifex clumps are good, if you have any of them handy!

what No termite mounds??? guess just sand and dirt hills would have to do.

Get a BLOB, the best target I've ever owned. Will last for many years.

I use old foam boogie boards bought from thrift stores. The type of foam board that's like the self-sealing foam targets.

The most I've paid for one is $3

I'll second the Blob will last for years.

The Blob??     That movie scared the bejeebers outta me when I was a Wee Nard!!  

sand banks ...

I've never shot a blob but I tried a rhino block and it doesn't take broadheads very well. I agree with the sand comment, it's rough on broadheads but works amazingly well.

I always start practicing for the fall by leaving a ladder leaning against a tree and sooting every morning.  One or two of my arrows are tipped with BHs.  I shoot those at objects ont eh ground rather than the deer target.  Takes a couple of seconds to clean the dirt out of them, but the ground never gets worn out  

yall must have different blobs than me, i got 8 of them when they delivered to tx 2 years ago and they are all shot to pieces!! This year i started shooting a new one with broadheads in july and it didnt last a month till it was in many pieces even shooting it on the narrow side, started on another and had the middle shot out in a week. I had better luck with the rhinehart 18n1. even a morrel six shooter has held up better for me(though it is shot on all 4 sides and has a huge hole through the middle).

An old pizza  box taped closed with the spray foam insulation sprayed into variously located holes in the box also works in a pinch. It just takes a day to dry. They don't last too long though.

18-1 reinheart works for me, but not as good price wise as dirt or sand banks.