great thread. Now I could look at this question a couple of ways:
Most expensive thing I have bought that
Razzman never uses: His very fancy Petit Pooch satin/silk bed at about $100 It sits gathering dust in our bedroom:
Second most expensive thing I have bought that we have used about 7 times: His very fancy expensive purse type carrier $300.
Rabies Titer at ~ $295 a time Wow that is one expensive titer!
Most expensive accumulation of grooming tools ever

Gawd help me has to be over $600 or more I truly don't want to add up the costs in me head!
A pro shoot day: He had a blast - I had trouble saying no to all the cute photos; ~~$2500
His most expensive Training and Fun Day at the docks $200
Now that I think about it; this is a depressing thread! ROFL