That's true about the cost Aggie, however, I'd have to spend a lot of time setting up the chemicals every time I want to print and spend more time pouring it away. In a slot processor, I believe the chemicals should not detoriate as fast due to exposure to air as the exposed surface area is minimal.
I don't intend to use plexiglass as it's hard to work with and it's expensive (as you say). Acrylic is cheaper, easier to work with and if it's good enough for Nova, it should be good enough for me.
I'm a little worried about sludge buildup, but I think I can deal with that at a later stage.