600w Belgian Sli bulb. Anyone know about it?

I recently bought a 600w Belgian made HPS bulb that is made by Sli. My hydro guy said it was good, but I don't really think he knows what he is talking about and it was the only 600w bulb he had in.
I paid about 85$ for it.
Anyone use this bulb, know about it, or know if that is a fair price for it?