I don't know other sources. I bought my Forever stems years ago from the original owner. However, I would point out that a few MM cobs come with acrylic stems if you shop for them and can find them. For example, MM and Dagner collaborate on a well designed poker nose warmer that has an acrylic stem and is available from either web site; I bought mine from the MM site. It has a fine ample bowl and is a commendable smoker. My wife bought me a extra large freehand MM cob which came with an acrylic stem, though I haven't seen that one online lately. It has a conical bowl. Both these cost a little more, but less than buying a similar cob and retrofitting it with an acrylic stem, even an inexpensive one.