what's up with the Kamoer FX-STP pumps? it's been out of stock for several months now on MD/BRS or other vendors. the only place to get it nowadays is eBay. the lack of inventory really concern me. can someone fill me in as to why that's the case or walk me off the ledge? i'm about to pull the trigger on the Kamoer on eBay that's coming from China.