Why buy an expensive 19″ rack when you can build it yourself for 8 Euro and a bit of work?
There is no magic here. The ingredients are really simple actually: A few pieces of wood, screws and glue.
The construction is rigid. No angles are required due to self-stability of the quadratic frames. Just make sure the inner length of each edge is exactly 19″ (48.26 cm). Glue and screw the pieces together and that’s it.