In addition to Archers, there is Woodland Scenes and a few other small vendors who do scale model related stuff.
There is also Letraset that used to be big for office products, before the days when personal computers began to do computer graphics. They mostly do lettering and numerals, in a number of sizes, colors and fonts. They also do things like math symbols and other symbols (electrical schematics and such). If you can find something that fits your needs, their product works great.
I just did a quick google search for dry transfers, and found there is a vendor selling products for make-your-own dry transfer lettering. I have not tried it yet, but have been making my own decals now for about ten years. Maybe it is time to try their process for dry transfers.