I understand where you're coming from, but I don't really think selling a few frags for a low price would end up lowering overall prices. Now, if you had a gargantuan colony of PL and flooded the market with $20 frags, you'd drive demand down and consequently, prices. Honestly, I think that those lucky enough to receive a cheap piece from you would be more "inclined" to sell frags from their growouts for a lower price, but more than likely, they'd be sold for market value, or a little below market value. The thought would be, "Why sell this frag valued at $100 for $20, when I can sell it for $80 just as easily?"
It's like the RBTA situation from back in the day. 4-5 years ago, I'd have to pay $200 for an RBTA, if I was lucky enough to find one. After the market got heavily flooded with RBTAs, prices dropped drastically. Now, people are practically giving away the things.