Try "makingitdigital.net" they make the inserts for the caps,
good quality and price, I've had them on my wheels for +2yrs.
I could never get them to respond to any e-mails when I was lookingI ordered the caps 2 weeks ago and I have received no response from makingitdigital.
Did they take a while when they made yours? I have not been able to elicit an email response from them either.