I predict you are in for a long wait.
Today, I just unboxed another IBM 5140 from eBay and harvested the keycaps. I like the Matias switches so much, I want to have dye-sub PBT keycaps ready for the Matias-switch keyboards I plan to order. The dye-sub PBT caps will be just for the alphanumeric keys; I am content to use ABS for the spacebar and modifiers.
Now I hope to reclaim some costs by selling the computers sans keycaps. I could also pull out the keyboards for those who would be interested in converting them to USB or harvesting the switches (brown Alps for the main keys and green Alps for the F-key half-height switches).