ROSA Gallery Monopigmented Professional Watercolor Paint Set, 12 Water Colors of 2.5 ml, High Lightfastness Paints Kit for Artists, Adult, Lightweight and Portable Metal Case

Ngl I'm kinda surprised that W&N wouldn't include a cool red. And that they have a blend for ultramarine and burnt sienna, both typically single pigment paints. If you're looking at gouache only, https://a.co/d/09ELfJhG would be a reasonable option. Edit: for watercolor, here is a reasonably priced single pigment set that is very popular: https://a.co/d/05Ozfudg (it doesn't contain purple, but it looks like a very mixable set)

Tiny watercolor set or drawing set. Spend half an hour really paying attention to your surroundings… it is very relaxing. Also, you end up with a souvenir of your trip for later. I like to bring a small journal, couple of waterproof pens, a pencil and travel watercolors. There are many kinds but Rosa, from Ukraine, is professional grade pigments and very affordable. https://a.co/d/06i4CoSPEdit: also bring a water brush like this one. https://a.co/d/08Z2JIGL