I can't comment on current prices, but I can say that I'm 100% happy with the springs, even as I come up on 50,000kms. I can't imagine not having them.
Thus far, out of everyone I've ever encountered with them, you are the only one that has had that happen.
Either that is straight up bad luck, or uh... Statistically, 1 product failure per x number produced is to be expected. So far, it seems that 'x' is pretty high, thus failure rate is very very low.
Overall, Eibach (the mfg of the DG springs) has a stellar reputation for quality. Much better than, achem, Vogtland.
Wouldnt have been an issue but DG spring warranty is only 1yr or 12,000 miles. Also I think incorrect installation by the dealer attributed to my failure.