Yes, it's true. The suites do change prices based on high and value season, but generally that's it.
We stayed at the GF in a 2 bedroom suite...let's just say each night was equal to one month's mortgage payment.

Grandpa footed the bill for that one so we could all stay together and he could spend time with the grandkids...obscenely expensive and no discounts!
And, may I add, we were really disappointed with the suite at GF. We were expected Deluxe hotel, and I would say our room was comparable to an average room at a Hilton hotel. It was certainly nice, and clean, but certainly NOT luxury. It is no Four Seasons. We stay at a lot of nice hotels, and wanted to stay at the nicest one in Disney--still, we weren't bowled over. (I hear they are putting a Four Seasons near Disney--can't wait to hear more about that and how it will affect Disney's so called "Deluxe" properties!)
That said, clearly Disney is having no problem filling these suites at these high rates!
PS--This year we're staying at Shades of Green, and our ENTIRE seven night stay, WITH the dining plan, is cheaper than one night in the suite at GF!