This is, in my opinion, a nice kit at a good price. Unfortunately, the trx is a bit large and I would have liked to have the operation from above… but that could probably be rebuilt.
I’d be tempted… but I already have enough devices. 
…what would totally turn me on would be a kit for 60m / 30m / 17m 
73 Armin
Check out the TR-25, good on 20m and 40m with loads of front panel controls
My kit was thoughtfully prepared and a joy to build
All the parts in the KX1 are standard through-hole components. You’ll always be able to find spare parts. The one exception I can think of is the microcontroller and the fact that it has to be programmed. But Elecraft would probably be able to offer some help with that.
I use my KX2 most often, but hands down my favorite CW-only QRP rig is my KX1. For the features it has it is more compact than anything else. It has a great built-in tuner option and can have up to 4 bands installed. For power I have used the internal battery holders for 4 LiFePo 14450 cells and two dummies. This give me 600 mAh at 12.7 volts, which is more than you need for one activation.
Through-hole components do go out of production. The 4-band board for the Elecraft K1 was discontinued in 2014 because the trimmer capacitors were no longer available. The K1 itself was discontinued in 2017 because parts were hard to get and expensive.
wunder
Wating waiting waiting for the TR-45
Maybe I missed it but uSDX by Manuel DL2MAN is an interesting, very compact and inexpensive option.
It is generally multiband CW rig with added SSB/AM/FM modes. I do not mean Chinese copies from Aliexpress or eBay, but 8 or 5 band kit you need to assembly your self.
I converted QCX Mini into uSDX and it works as well as any QCX I have. New version with 3D case should be available shortly.
I emailed Ryan from LNR Precision and asked if there might be another production run of the MTR3b. Here is what he had to say:
It is doubtul on the 3b. It was a completely different PCB and enclosure and the designer did major improvements on the 4b and wants to centralize around it. Its possible we will offer different bands on the 4b platform in the future, but the 3b is essentially retired. You may be able to pick up one second hand but they are hard to come by. Thanks!
Ryan, LNR
So there you have it: MTR3b is officially retired.
73 de OE6FEG
MattDespite having discontinued the KX1, Elecraft still sells updated KX1 programmed microcontrollers. FW KX1_KX1 Firmware Upgrade 1.02 – Elecraft The update mainly is to provide support for the expansion board that adds 80m and 30m coverage to the base model which only covered 40m and 20m.
I was fortunate enough to find a used KX1 with built-in ATU. I’ve been delighted and use it exclusively for my HF SOTA activations.
Up until recently, they were contemplating another run of the 3B next year.
Maybe if enough people email them, they will change their minds. I love the smaller form factor of the 3B and don’t see the need for 80 meters as an additional band. I have an older kit built 3B with 40/20/17 meters, but would love to see a 60/30/17 combo. I keep looking for used 3Bs for sale, but they usually only last minutes once they are posted for sale.
73, pat - ki4svm