Go to Gunbroker.com and do an advanced search on completed auctions using the search term "Smith Wesson Highway Patrolman" and "Smith Wesson 28". You will see a lot of auctions. You want to look at the ones that actually sold (Received a bid).
I just did a search using the term "Smith Wesson Highway Patrolman". It returned 463 matches. On the front page of the search there are six 4" barreled versions that have sold between 25 July 2017 and 18 August 2017. The lowest winning bid was $450. Highest winning bid was $800. Average auction sale price of those six revolvers was $634.17. Condition on these six varied from about 85% to NNIB. Some had replacement stocks, some had factory wood. Only you know the condition of your revolver that was stolen.
I'll leave it up to you to do the search for "Smith Wesson 28" and look for the auctions that resulted in a sale.
Class III