You might find optical-grade resin filters as noted in the previous post, but they need more careful handling than glass. Sinar had the best ones, and you might be able to find a set now that many
studios have gone digital. But really, most ordinary colorheads are a piece of cake to work. If you can make your own coffee in the morning you can figure these out. And certain so-called VC heads are simply colorheads with either the cyan or red filter removed and the feeback circuitry recalibrated. I'd avoid the Beseler/Minolta. It's a weak flashtube system that might lead to unpredictable results when dodging/burning. Split
printing just takes a little practice, if that route appeals to you. I can practically do it asleep. It can
be done with red and blue filters somewhat more efficiently than yellow and magenta, but either way
works.