Check Ebay, etc., there are many types of reactors and many of them are extremely cheap. Also remember that the majority of the costs listed above for the DIY version were for the sugar, yeast, etc... so if you take that out of the equation you see how much cheaper the DIY materials actually are.
Also, the DIY recipe I use doesn't involve Jello, it's just water, sugar, and yeast. I've been getting high production for about 5 weeks now, and in the last few days it's finally ramping down.
I personally like the little glass reactor/diffusers better than the ladders, they're smaller and they can be hidden behind a plant more easily. However, my opinion is based solely on my aesthetic taste; I have no idea which one actually works better

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I'm using the DIY setup on a 3 gallon nano planted tank, so a diffuser would probably put my CO2 numbers over the top; I just send it through an airstone, and after this inefficient mixing my tank has dropped in PH significantly