What do you suppose an unsmoked 1935 Dunhill, complete with original box and sock would go for? $2000? $4000? What's so amazing about $300 for a Parker?
Yes it was set up to handle what Dunhill referred to as its "failings". What exactly does that mean? Does it mean that the wood was bad? Ofcourse not. Maybe the block didn't have the kind of figure that met Dunhill's metric. The pipe shaped from that block at the Parker facility might have turned out to be an exceptional piece.
We know that Parker made pipes from wood that weren't Dunhill leavings. They bought wood on the open market as well. We know that some of those failings, when fully shaped, went back to Dunhill because the process of removing the "offending" wood revealed a pipe of top notch quality. They didn't just make "seconds".
Of all the top makers, only two were known to control their briar from the ground to the counter, Barling, and for a while, Comoy. Everyone else bought from brokers, including Dunhill.
The rules for "collectors" are different from the mass market. Depending on their focus of interest they are pursuing the best available examples, and unsmoked vintage pipes are a rarity amongst rarities. People who love Parkers, and there are a lot of them, are going to pay for something that might become a centerpiece of a collection.
All things considered, $300, or even twice that, for an unsmoked Parker from the 1930's, in a complete set up, isn't much of a stretch.