While rambling around the internet today I ran across a copied email stating the supply of on shelf repair parts for K3's is dwindling. If you think you might need a replacement or upgrade you might look into purchasing very soon.
From the email... I do not have direct knowledge this is true...
*Here's the status I got on December 30th*: (I'll bet it's changed a bunch since then. NOTE: this is only a list of statuses on the parts I was ordering.)
* KRX3A: 9 available as refurbished (reworked, not necessarily used).
* KBPF3A: plenty of stock available for the foreseeable future
* K144xv: we have only a handful of these at this time.
Undetermined whether or not there will be another work order for
purchase from vendor.
* K144rflk: we have approximately 10 in stock - most in refurbished
* KFL3A-6K: limited availability
* KFL3a-2.8: we have about 15 or 20 of these at this time. If we did
not have them available when you want them you could most likely buy
them directly from our vendor (Vibroplex).
* KFL3A-400: this is probably one of the 2 most popular K3/K3S
filters. We do have a good number of these available at this
time but they will probably go fast
* SP3; we have 25 of these available at this time. Undetermined
whether or not there will be another work order for purchase/build.