You can make a dowel plate quite easily at home if you want to churn them out yourself in the workshop. Numerous guides to this online, If you want them fluted you can squeeze the dowels in a pliers or vice grip or just saw a groove in instead.
Making them yourself is a useful way of using up small scraps of hardwood that may not have any other practical purpose, plus you can have them in species that aren't available commercially if that might prove useful.