It's been my experience that when buying from hot rod or 'speed shops', that unless you are buying something super sexy, like a 8-71 supercharger, or big buck item.....Dumb @ss syndrome definitely applies....the guys just don't think of the small purchaser in the same light....too bad...good customer service is hard to find.
You could try the machine shops...they tend to have all kinds of 'junk' laying around and you can sometimes get it for free. When I bought and installed the Vortec heads on my truck, my machine shop gave me a set of valve covers (center bolt....I only has old style side bolt). They even ran them through the wash bay for me....all for a nominal price of $10.
Tim