The king of HiWall actions would be a thickwall blued centerfire solid frame with coil mainspring. If such a prize showed up at a gun show my guess it would be priced at over $1500. On the other hand a thinwall blued .22RF Winder Musket coilspring action can be had for half that. Although musket actions are softer, they IMO will handle any load in any black powder cartridge with absolute security. And though "scarce", they are not rare. It is still possible to buy complete HiWall Muskets for under a thousand bucks in good condition. I would much rather start with such a Winchester action that with any of the clones.