Hi artxty,

As these are sold by individuals as one-off sales, the seller of my manual probably has no more available.
Below are four sites I have found via Mr G that may still have one for sale:

https://www.ebay.com/itm/Honda-Genuine-Shop-Service-Manual-GV400-GV-400-K1-KI-/254190335751?_ul=IN
This does not appear to include the supplements

https://www.amazon.com/Honda-Engine-Service-Repair-Manual/dp/B00D46TPGC
This has a different cover to mine but appears to include the supplements K0 & K1

https://picclick.com/Honda-GV400-Engine-Service-Shop-Repair-Workshop-Shop-373608998815.html
This appear to include only the K0 supplement and not the K1

https://www.ebay.com/itm/3828712353...0&campid=5338722076&toolid=10001
This appear to include the supplements K0 & K1 and has the same Publication No as mine

Looks like eBay is the place to start.

Cheers, R