Gree, I think this is a bit extreme.
Level 250 takes 250k gold for an open
Level 150 takes 150k.
Free players will not have many of the gem gold buildings and won't be able to afford the gold hits.
I realize that you want peeps to use the 5 gem open instead, but many won't do that and will just stop this event once the guild quest is finished, or not even bother in the first place.
You need to reduce the gold opens back to where they were.