Bluestem Nursery is an excellent source for OG plugs. Not aware of any place that will sell wholesale without being involved in the industry but I guess there could be some out there. I would also consider asking my local nursery to special order in the quantity you need - most retail garden centers will do that provided they are give sufficient lead time and will often discount based just on quantity. Not the same prices as wholesale certainly but often enough of a reduction to make it worthwhile.

I second Bluestem Nursery. Early this year I ordered a pack of 25 plugs of Eligah blue festuca, very reasonably priced. Customer service is excellent. After my order they called me to tell me the plants I wanted were not in good shape at that time and would it be okay if I waited until they started some new ones. I said yes, but later they called to tell me the starts were not taking well and offered an alternative. I accepted and they were sent out immediately. Very nice plugs and I planted them and they are all doing well. They also sent me 3 different bonus plants. I appreciated the way they kept me updated and wanted to be sure I was happy with the plants I received.

Bluestem Nursery is based out of British Columbia, Canada, but I see it has a USA address as well.