We bought 100 points at OKW two months ago and the closing costs were $375.
The costs go up in increments of $25 as you get more points (higher total purchase price). I forget what level the tiers were, but I think at 150 points you'd be looking at either $400 or $425.
We closed May 2nd on 170 points. Closing costs were $450. We brought resale from a friend. We used Timeshare Closing Services, which did a great job. Very fast and helpful. Closing fee was by purchase price.