If you start with DIY CO2, do use the aseptic technique and also use an equal part yeast to baking soda in the mix. I have found the baking soda is critical to maintaining an even output throughout the batch life. If you're a tinkerer and enjoy science experiments, adjusting the yeast, food for the yeast, etc.. can be very relaxing. Each method have their pros and cons, DIY having less likelihood of gassing your tank, but could become messy. A well made paintball system would likely be your best bet, but if you have the funds a nice timed setup with the bells and whistles will give you the best and most consistent delivery of CO2. There are great threads for all methods, it really falls to what fits your budget and time as DIY does take some time - I have a Fluval 20g and DIY CO2, and prefer the DIY for the constant output over turning a system on and off daily. Also, with the DIY I set it and forget it. I basically check it daily when watching my fish to ensure the output is normal. As for refreshing the batch I now try to mix a new batch of CO2 a day prior to my 50% water change to compensate for the initial burst of CO2 and allow the batch to mature. I use 2 12oz generator bottles and a gas separator. If you do not have a check valve for each bottle, at least have one on the line to the tank. Also, something I really didn't read about for people using more than one bottle without a check valve on each to depressurize the system unscrew the cap on the gas separator bottle first, otherwise you'll have a mess.
There are many techniques for diffusing DIY CO2 also, I have found the Fluval 88 ceramic diffuser works perfect for this system and is only about $6 on Amazon. Any "nano" sized diffuser should work, so long as the seller does not advise pressurized system only.
Good luck with which ever option you choose, just wanted to share my experience so far with the DIY. I really do not understand what is such a chore about the DIY CO2, it only takes me about 30 minutes weekly to heat my spare 20oz of filtered water from my fridge to 105*F, measure yeast, sugar, and baking soda. I use a small harbor freight funnel, pour the ingredients into the bottle, cap, shake, wait about 1hr cracking the cap to release pressure every 15-20 minutes. Then I depressurize my system, disconnect the bottles, rinse, and pour in the new mix - reconnect... and done. So far I have spent about $20 for the silicone tubing, fittings, check valve, and diffuser. I bought some 12oz coke zero bottles since I thought they looked cool, which was like $3 for a 6 pack so I have back-up bottles/ caps. Just use an 11/64" bit, drill from the inside of the cap to the outside then cut your tubing at an angle and use needle nose pliers to pull the tubing through the cap and it will create an airtight seal. Cut off the end of the hose once through the cap to clean up the edge as it will damage it a bit pulling through the cap. Either system will require the diffuser, check valve, and tubing - so DIY is the most economical system. I bought the baking yeast jar for $5, should last me at least half a year.
Great site for DIY CO2 and the science behind it: