We typically fly to WDW in June (2nd or 3rd week). I usually begin looking for airfare as soon as prices for the time period become available--10 months out or so--and buy as early as I can. This year, though, our trip was totally unplanned and spur of the moment (for us that is) and I just purchased in January. I've found, at least for June, the prices tend to go higher as the date approaches.
Our fare for this year was $194 per ticket (Toledo); last year was a bit less at around $176 (originally Toledo, but changed to Detroit due to ComAir strike); years prior to that ranged from $176 to $210 with the latter being a direct flight from Detroit to MCO on NW. I, personally, loved the 7:00 a.m. NW flight which arrives at around 9:20 a.m. Unfortunately, that flight now runs around $250-263 and is unreasonable when you can arrive a couple hours later for a good bit less.
Delta's rates appear to be better than most others, including Spirit which is usually the least. Who knows, the price may drop if the seats remain available--since we are 4, I don't like taking the risk AND I like to have a choice in our times (early in, late return).
Good luck!