Yes, compared to typical prices for the balls it is a good deal.
However, I'm going to assume that they got some kind of discount...probably a bulk deal like a buy 4 / get one free. Even small shops can get that kind of a discount at trades shows, etc. If that is the case then the price is indicative of them passing along the savings to their customers. If you take standard online costs and extrapolate what the cost would be if they got such a seal...the package should sell for around $320-ish.
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-Chris: DJ's Pro Shop : Auburn, MA