DIY CO2 certainly does create suffiicient pressure to diffuse through a ceramic diffuser. If it doesn't work for you, there is a leak in your system or your system isn't generating enough gas pressure to do so.
Honestly, I'd scrap the DIY and set up a paintball system if money is an issue. I followed the plans outlined on here and made a sweet set-up for less than 30 dollars. No more loss, no more changing nasty bottles, etc.. DIY is fun for a while, but the magic wears off quickly. Haha. Anyway, just throw a cheapo nano diffuser on it and you'll be good to go.