Where do you think I could get a pressure cartridge, or a few actually in a timely manner? I am really looking for quality here and so that makes it raised up to high standards. I want the best in the business. I am not in a terrible rush, though timeliness is something I value. Perhaps looking online is the best way to go. It is much more vast than an electronics store I think. I can get my items expedited and shipped to me from that broad range selection. So from here I can go to http://www.networkselectronic.com/Products/PressureCartridges.aspx and get just what I need. I recommend others who are looking for electronic components and elements that they go on here, online directly. I have ordered from them in the past off of this website and have been very pleased. So to answer the original question, online is where you go to shop for these kinds of pieces. You will not be disappointed.