hi welcome!
what kind of package is it? how old is it? which series is it? (master, provid, sk, efp, etc.. glidecam...)
is the seller offering any accesories outside of the basic package you could get on your own?
if its in good condition then 30K US is kinda a standard price i have seen. if s/he has more items or a much newer Rig it could cost a bit more...