I'm with you. I don't need starting materials, but I like those models. I also would prefer to leave intro boxes in stock for new players. Having existing players eat up the stock of the set to get the miniatures they desire results in intro sets going out of stock, which is annoying for Catalyst.
I need to underline this:
buy as many boxes as you want.
What's far more annoying for Catalyst and your LGS is having lots of unsold product sitting on store shelves. All that does is delay the return on CGL's investment, and tell the store owner that it's not worth stocking any more BattleTech because it doesn't move. Sales volume and velocity are key for both reprints of these boxes and additional product.
I've seen this idea before, "I want to leave intro boxes for new players." Most likely, you're only leaving them for the mark-down clearance bin. Especially if you're not also demoing the game, playing it in store with your regular group, and talking to the store owner about it.
Instead of waiting for the product to sell itself, why not give it a hand? Demo the game, or arrange a beginner's grinder, with the winner getting a Beginner Box of their own. Part of the reason to have a $20 box is to make it more possible for existing players to use them as tools to help spread the word. I can't personally afford to give out lots of $60 boxes. But $20 boxes are much more possible as tournament prizes, passing along to a friend as a gift, etc.