Hi Jessica,
Before delving into your question, I consulted the Oregon Department of Agriculture approved invertebrate list to make sure trade in puncturevine weevils is allowed in Oregon without a special permit. And luckily, both puncturevine seed weevils and puncturevine stem weevils are on this approved list.

As far as sources of these weevils go, I am not sure if anyone currently sells these weevils in Oregon. I did find some news stories from 2005 and 2018 indicating that Roak TenEyck, owner of a company called IRV Goatsheads in Umatilla County, was selling them, but I am not sure if he still sells them. One article listed his phone number as<personal data hidden>, so you could try that number to see if he is still in the business of providing puncturevine weevils.

Also, you may consider whether you actually need to buy puncturevine weevils. The Oregon Department of Agriculture reports that there are many areas in central & eastern Oregon where there are widespread, self-sustaining populations of puncturevine weevils, so they may already be on your property.
https://www.oregon.gov/oda/shared/Documents/Publications/Weeds/PuncturevineProfile.pdf

In addition, Deschutes County has a publication that goes over best management practices for puncturevine control, and that can give you some ideas of additional options.https://www.deschutes.org/sites/default/files/fileattachments/road/page/1690/puncturevine_bmp.pdf

Hope that helps!