So, I was cruising the old threads looking for demand valve info, and I thought, shoot I'll just ask everyone what they recommend. I found one without a mask on Ebay for $185. It's a allied healthcare L063-05R. Is that the best price I'm going to find? And I'm wondering how big the quality gap is between the cheaper and "sell an organ for" price range. I'm looking to step up my O2 game. Any and all advice appreciated.