~$500 million Pelco valuation:
Assume ~$300 million annual revenue, track record of revenue decline, limited growth potential.
Historical comparables are in the 1x to 3x Price to sales range. ~1x is for OEMs or bad manufacturers; 2x is for solid companies, 3x is for strong companies.
With that rule of thumb, $300 million valuation (1x) seems low, Pelco has lots of problems but still has a premium, though receding brand. $900 million valuation (3x) seems to hard to justify because of declining sales. ~$500 is roughly in the middle.
Ultimately, companies are worth whatever the top bidder wants to bid, but based on historical comparables and Pelco's revenue / decline, ~$500 million range is sensible.