This is the dll found in 1.0.3-rc11 of the original project, although it is not flagged as prerelease by NuGet which should allow using it as a dependency without flagging your own library as a pre release.
SteamStoreQuery - C# Steam store querying library.
This library allows you to search the steam store and returns a list of objects containing the listing name, price (USD), store link, image link, and app id.