You can actually make these pretty easily. Search TFF for the words "weir" and "overflow" and you'll prob find atleast 2 or 3 DIY's from the hardware section. If not, then just go on google and search weir and you should get a good amount of pages that have DIY. If you don't wanna DIY then they can be a little on the pricey side but if you look for a bit, you can find some decent designs.
A better option that would be easier too is just using bent tubing. I've heard of doing this and if i do a sump then I will try this method. Just use some PVC tubing to make an s and that goes in the tank and it works basically under the same principle that your syphon hose does. With no air pressure allowed to enter and the water moving through the pipe, it creates a pressure difference like a straw so the water from the tank is pulled through the s section until gravity takes over on the outside of the tank. Its really quite simple
