The Demoulin set is one that I have never acquired. Been offered a set (might have been from Dunathan contact but it's been so long I can't really recall) and I've seen a nice set for sale. The price point just puts it out of my metal-squirt-gun budget. I got into metal squirt guns because in many cases they are sold so cheaply compared to other antique toys. For the most part, about $100 is my upper range. For the same reason, the space/ray gun portion of my collection is far from being definitive.
Some years back, there was a camera setup as a squirt gun which I sort of recall also being Demoulin. Recall going deep at something like $200 or so and got outbid by a large margin.
Although I am almost certainly the most active metal squirt gun buyer in the world, I have my limits.