Welcome to FT!

Price is based a lot on supply and demand and it changes accordingly in the morning, afternoon and evening.

In your case, if you checked AC's website all week and price showed as $89, then it was a very good good deal and it's probably gone as seats gets filled. I suggest you run a search in the evening because price may also be lower. If it's not the case, you better book the $149 and not wait longer as this price may change and go higher.

If you call AC, they will not really offer you the lowest price and for your information, there's also a booking fee if you make this booking over the phone.