Buy a cheaper set of DCs and then call DC. They will send you the kids bands. Easy to install and work on my 4 year old just fine. Full size head clamps just fell off. The kids DCs are just fine.
Be sure to look on EBay, there are some really good deals on DCs over there. I assume other brands as well, but I had to quit browsing because I was tempted to keep buying extra headsets I don't need.
+1 on the dc idea. Someone suggested the same thing to me, I emailed them and they simply asked how many conversion kits I needed. IIRC they didn't even charge for shipping.