Are replacement stems easy to come by? I'm wondering as I frequently see nice bowls with stems missing on Ebay. Do manufacturers make replacement stems, and if so how hard is it to find one that will fit well in your pipe? Here I'm asking about large manufacturers like Savinelli and Peterson, any company that does that level of volume has to have spares, right? And how economical would they be? After all there's no point in it if the whole process would leave me spending more than for a complete pipe.