I thought it would help to make a post that helps to explain CO2 costs. Please feel free too add the cost of your setups, brand names and anything that will help others decide if pressurized or DIY is they way they want to go.
DIY CO2 is inexpensive and costs less than a standard pressurized setup. DIY costs will be less than a pressurized system for about 2 years. DIY is however very unreliable and it is hard to keep levels at steady 30-50ppm. Pressurized CO2 is expensive to start out but once it is set up you can almost forgte about until you need to refill. You also can not turn off DIY nor regulate it so that you don't have a pH crash or give your fish CO2 poisoning. If you have the money, pressurized is the way to go. Either way, CO2 in any planted tank will increase plant growth and help prevent alot of algae problems. That is if you can keep your CO2 levels between 30-50ppm using DIY. Levels that fluctuate below 30ppm with any CO2 can actually cause worse algae problems than not using it at all.
Some cost information:
sugar, yeast, two 2 liter bottles, airline, silicone, check valves and if you really want to a fancy diffusor. Total cost is about $35-50 and about $100-125 with a good diffusor system. Then it costs about $4-7 a month to maintain for every two 2 liter bottles for yeast and sugar.
10 lb. CO2 Tank: $90-120
pH controller: $100-150 ( not "needed" but if going high light and do not want to turn it off and on and check pH 2-3 times day it is priceless)
Check Valves: $5-10 each for top quality ones.
Bubble counter: $10-20
CO2 Diffusor: DIY with powerhead - $60
Refills once a year are about $20
Yes there are complete setups with 2-5Lb bottles, cheap regulators another items that you can get but I have not seen any of them that carry the warrenties you see with good quality systems nor the reliability reviews from those who use the higher quality components. Even then a descent one is gonna run from $250-400.
As you can see, it can get very expensive to get a medium quality pressurized CO2 system and everyone that I have ever talked to about this says this is not a place you want to skimp on quality. Cheap regulators fail over time and can get jammed because of poor quality needles. Cheap pH controller will fail and are much harder to maintain. If you are going to spend all that money for pressurized, a good diffusor not one of those ladder thingys is best. After all, if you are going to pay for pressurized you want it to all be useful to the tank and not have a majority of it escaping out the top of the tank.
Top quality CO2 systems will cost about $150 more.
Last but not least, if I ever decide to get pressurized CO2 you can guarantee I will do it right. Spending an extra $100-300 will pay for itself in the long run in peace of mind not to mention the safety of our fish, a lot less algae and a lot less maintenance.