You want to take Your time and don't buy the first one that catches Your eye. There are way to many for sale to pay a large amount of money for one. The market is glutted with them so You must really research any one pipe before buying it. Enjoy Your choice just don't get taken for a ride they aren't worth that much.
It's a shame they don't go for more. Every true artists work goes for more money after they are dead and gone. With Preben's stuff, I think the market for them hit its monetary peak in the 70's. You can get them for little money these days if you look hard enough. We can't take money with us when we die. I think the admiration of the few that still love his work have more true substance than any monetary gain. I hope his spirit is satisfied.