I think they were sold individually, but we're talking a long time ago here - the last one came out in 2013-2014 IIRC. I was more into Feral Rex - which I got, and still love despite a few minor design flaws - so I didn't pay much attention to War Lord back in the day.

Either way, there's next to no point looking for one on BBTS/TFSource etc. If you want one then hunt around second-hand sales boards on the big international TF fan websites (i.e. US or East Asian if you can navigate the language issue). You might get lucky on Mandarake, maybe even gumtree etc. as well. But yeah, ultimately it'll just be a matter of waiting until you find one for sale at a price you can bear.