I have been getting daily alerts and yes the prices have gone up in the last week or so, but I think they will come down again try Liligo.com and get daily updates.
Last year I booked on 12th June for £2436, this was for 5 people 9,11,18 and two adults for Monday 21st October through travelup, the customer service was terrible but once i had the flight details I phoned Delta direct who were very helpful, sorted the meal requirements, told me how to book the seats etc, and all was good.
Must tell you though, when I phoned travel up they told me there were no flights at that price, however on their website the flights were there and thats what I paid. In fact everywhere I phoned they told me the prices were more than what was on their websites!!!
I looked everywhere for flights, Asda, net flights and Disney themselves were all similar prices. It does seem cheaper to fly on the Monday, which is what we are doing again this year. My children get two weeks half term and yes they do miss two days of school but not a problem at our school.
We didn't take the dining plan last year and when I added up what we spent on food it was cheaper than what the dining plan cost, we also ate at the restaurants we wanted to. The dining plan would have given us desserts but we would rather eat starters, one of the children would have had an adults plan, but he actually ate children's meals (so I new I would save here). We also ordered from garden grocer, so most mornings had breakfast in the room and had fruit, drinks and snacks to take with us to the parks. So may be worth comparing prices from disney Uk without the free dining