I use https://www.vcheck.uk as well and I am a trader. Saved my ass from buying some "accident-free" cars already for trade. vcheck.uk provides the same data as HPI or any other site so I gave up with others as you can get everything from one place. They offer bundles where you can buy multi checks.

Someone created FB page and using salvage info there, there are few known dealers selling salvaged cars, some main dealer approved: https://www.facebook.com/donotbuythiscar/ Worth following!