Another option is to ask if your local drum shop will do it for you. They should have the experience to give you peace of mind and you won't have to spend time looking for very large boxes.
These guys are not in your neighborhood, but Columbus (Ohio) Pro Percussion shipped a set to me that I did not buy from them two years ago and did a superb job. I thought their price was very fair and it apparently left the store the day I dropped it off.
I'm running into some snags finding the boxes, as the kick is 24X14, meaning I'll need at least a 26X26X16 box.
After I left the "corporate world" I owned a UPS Store (it was Mail Boxes Etc. then) for awhile. UPS, Fed Ex, etc. are great companies and do a great job, but being gentle with packages is not their priority. A 26X26X16 box only gives you 1" on each side for packing material...that isn't enough. For that size (they call it "oversize") you're going to pay the 70 lb. minimum anyway so you might as well have a wooden crate made for the bass and probably the floor tom. Just my opinion...
you think 24 x24 are enough i like to go bigger and then add a inner wall of Styrofoam it stabilizes the bigger box more try a 28 inch bd man that was a tough one for me but i used double walls and a lot of packing take your time and do it right to avoid a costly mistake and a crying customer good luck
