It may be very difficult for you to find these plants, and even more difficult to find "clean plants." It will be very challenging to find the few vines that you need from a nursery (most require minimum orders of 50-500 vines). I also do not know of any Petit Verdot producers locally who can provide you these cuttings.
When sourcing plant materials, it is important to consider obtaining grapevines that are clean, meaning that they are not infected with important grapevine viruses that are passed through cuttings and that cause concern for plant health and longevity. This has been an increasing concern in the grape industry, as new viruses have been identified recently (e.g. Red Blotch Disease) that can jeopardize fruit ripening. If you are a commercial producer, this is a very serious concern. If you are a homeowner, it is still a concern, as you could be creating a disease source that may infect the commercial industry vineyards.
It is not advised to obtain cuttings from anywhere unless the source vines are tested and confirmed to be free of important diseases. There may be some producers in the state that have this cultivar, but it is best to have the source wood tested to confirm it is not diseased before taking cuttings to plant out in your vineyard. There are commercial labs that conduct grapevine virus testing. The important viruses cannot be detected visually and thus need to be confirmed through laboratory testing.
To learn more about clean plant materials and virus testing, please see the following resources:
National Clean Plant Network - Grape Program--ensures clean nursery stock, read more here.
Red Blotch Disease Fact sheet - learn about a serious grapevine virus spread by cuttings
Oregon Department of Agriculture - Red Blotch Fact Sheet