I've been talking to a supplier of back-plate Isolated K67/87 style capsules with 3um diaphragms for suitable for use in the U87i Circuit and was considering offering them at a group buy price of around $95.00 USD including shipping. PM or email me if interested. I'll add a feeler thread to the mic forum also and make a donation to group diy if it go's ahead. here a pic of a sample I ordered.