Vendors that we used and recommended in past include:
Plant Cell Technology
Links to these and others will come soon. Caisson Labs might offer a discount to KCK customers. I am looking into that now. Note that when you order from other companies, ask for cheaping shipping rates which are usually USPS. I did this recently with one company and saved $10.
If you have a favorite vendor, please email me with their name and contact information email@example.com