Never. I do it all myself. The planning is part of the fun!
I do keep a close watch on discounts, etc. It's not that hard to do. If you go to mousesavers.com, you can see a chart listing historical release dates for discounts. Not that these dates mean that's what'll happen in the future, but it does give one a good idea of when to start looking for particular timeframes. For example, for the past several years, discounts for stays in the beginning of the year (Jan-Mar or so) have usually come out sometime between the last week of September and the first week of October.
I've found that subscribing to things like "January discount" threads doesn't always work out, because usually by the time the discount comes out, everyone's on another thread!
Last year I discovered, while reading this very board, that booking through Orbitz can be an even better deal than booking directly through WDW. So my last two trips have been booked through Orbitz. You can stack the Orbitz discount code on top of the WDW discount (assuming there's availability at the resort you want). It does require watching for not just the WDW discount but also the Orbitz discount, but it was well worth doing.
If you enjoy the planning part of the trip at all, it's really not all that hard to plan a WDW vacation by yourself. Especially with the help of these forums, mousesavers.com, and allears.net.
Have fun on your next trip!