Venue Mistake

I’ve been looking nonstop for venues in the Houston area that I LOVE. I originally wanted a destination wedding but my Fiancé was not a fan of the idea, I decided to compromise and find something that I loved just as much close to home. I did a few tours and and found one that I was amazed by, they prepared a proposal for 150 guests and the price was very affordable and within my budget. Fast forward to a week later and an employee of the venue contacts me and offers 10% off the venue rental fee if I signed the contract within 24 hours. She sent over a new proposal that included the “10% off” and the overall total increased by $10,000. When I questioned the amount she stated that the original proposal was incorrect because she forgot to include the rental fee in the quote. I already had my hopes up and started planning ideas around this specific venue and now I’m back at square one. At this point I either negotiate to see if they’re willing to come down on the rental fee or go to the court house and call it a day. Has anyone experienced something like this? If so were you able to negotiate a price you were more comfortable with?