I've got four OEM Nikon battery grips. Two of them came as a premium (free of charge) when I purchased the respective camera, one I was given by an acquaintance who had no ues for it, and the last of them I just purchased used a bit over a month ago for a bit over US $150 after sales taxes were added. I had sworn off all battery grips a while ago, but found that the battery life with my D500 was always ending at a very inopportune time, so I opted to get the grip to try with the D500. The jury is still out since I haven't used it enough to exhaust one battery yet.
I have used a third party grip on my D90 earlier, and I don't remember having any operational issues with it, other than it looked and felt cheap. I don't recall that it even had a brand name on it, but just a "for Nikon D90" inscription, or something like that. I chose not to keep it because I was ill-at-ease with using it with my camera.
All-in-all, campared to the other expenses incurred with photography, an OEM grip is inexpensive; typically about how much a few nights at a hotel will cost you, at the most.
W