In pico DLP projectors two right angle prisms are used for directing the light beam onto the DMD chip and then towards the projector's imaging lens. X-cubes aren't used in smaller ones but are used in every 3LCD and 3DLP I know of. This is just anecdotal evidence from my observations and judging just by how it looks to the naked eye rather than a measurement with a sensor but it has appeared to me that with laser beams the light loss from prisms is more noticeable than with LEDs. There may be a reason behind it or it could just be me.
Some chinese sellers sell "defective" trichroic cubes for much cheaper (around 10 USD) but I haven't gotten a clear answer from any of them why they are defective or what that means. They say they don't have scratches and produced by them rather than extracted from old equipment or taken from an old warehouse for old TVs/projectors. Maybe are the ones that haven't met a certain tolerance requirement or something along the lines. Considering the price I may just get two and check them out.
There are also chinese sellers of "damaged" trichroic cubes with some scratches and also some scuffs around the edges of the prism. No idea where they get those and why they are as damaged as they are but they have quite a number in stock and sell them as "educational and decorative".
You can find them on alibaba, aliexpress, banggood and gearbest and some damaged ones on ebay.