The last time our club had an off-flavor session earlier this year, I ordered the kit directly from Siebel. They ship from Germany, which was not inexpensive. Maybe you've already discovered that.
The BJCP has a subsidized kit for BJCP members, at $100 U.S. and I don't know about shipping.
You might try exploring cicerone.org which also sells sensory kits. They're also expensive. Neither option really makes a lot of economic sense unless you have other homebrewers or a local club to help share the costs.