Well, I have only 1 pinned Japanese beetle in my bug collection. My six-year-old daughter collected it and pinned it, so the pin is off at an odd angle and the legs are dangling down too far. I suppose you could relax it and re-pin it if worse comes to worse.
If your customer could wait until around the middle of June, I'm sure I could provide you with tens of thousands of Japanese beetles!
Hmm... While I was sitting here, I thought about Constance Hurt (The Butterfly Lady) over at Butterflies and Things (www.Butterfliesandthings.com). I don't see any Japanese Beetles listed on her site, but I know she has some awesome contacts for bug wranglers, and she has always come through for me. As an added bonus, she's got some of the best prices around!
Her telephone number is: (330) 648-1406.
Give her a call and I'm fairly certain she can help you out.
Cheers