Not sure of the status of the Gustav but I had one in the 90's, model 1891 I think. It was the best shooting surplus rifle I have ever come across.
I regret selling it a few years back. Definitely a great deer-slayer for those interested.
I have an FNP9 with three (3) mags, gun is practically new, each mag only testfired, w/original box, preferably FTF in DFW
$475.00
Will trade for Walther PPS in 9mm or HK with LEM trigger + cash