In order to answer your question, you need understand that there are different rebrethers and they each have different costs, features, and maintainance requirements; however, most are somewhat similar, especially from a relative cost standpoint. Three to four months ago, I purchase a Dive Rite Optima Closed-Circuit Rebreather, so I'd be happy to breakdown my experience of the costs and time involved:
First, there's the rebreather, which cost me approximately $7K. Then you need to buy tanks for it (twin 13 cu ft doubles), which cost me another $400 or so. Then you need to buy the wing and back plate for your rebreather - I went with a Dive Rite Nomad system, which comes with the soft Transpac backplate and a side mount kit, that cost me another $700 or so.
So by my math, I'm already at approximately $8K+
The next item is training, which can vary a bit, depending on the instructor and the structure of the class. Mine was done locally with a top notch Optima instructor (Mark from
Fill Express -- Nitrox & Technical Diving Specialist Serving Greater Fort Lauderdale and
Dive Rite Express). My class was essentially done as a provate class at my convenience. It took a few weeks, after completing a few days of equipment assembly and lectures, because we scheduled the dives (8 dives) when schedules permitted - That cost me $2000, with all boat fees, fills and consumables included.
So, now we're comfortably over $10K
For the class, you need a bailout (pony) bottle with a regulator. Some people use an onboard bailout system, but the truth is, unless you have very large tanks within your rebreather, it's not enough gas, so most use an external bailout. Many people have them, so they do not have to purchase them again. A forty cu ft tank is the ideal tank, with its own individual o2 clean regulator. If you do not own that, then that will run you approx. $400 to $500, depending on the regulator and where you buy it.
So, now your somewhere around $10,500 or so.
After completing my training, and also taking into consideration that I was going to use the computer for deep decompression wreck diving, I realized how unreliable the oxygen sensors on rebreather actually are; consequently, I made the decision to add a fourth sensor and connect it to an independant computer that calculated decompression based on the fourth cell (an additional safety consideration). I chose to purchase a VR3 computer and added all the bells and whistles they sell for it (i.e., color screen, VPM decompression modeling, large screen lettering option, computer downloading option, etc.) - That set me back somewhere close to $2,500 or so.
So, now your at about $13,000 or so.
Please keep in mind, that everytime I walk into a dive shop, there's always something to purchase, I never leave empty handed. That phenomenom is somehow multiplied when you have a rebreather, especially at first. Things like reels, lift bags, spare parts, batteries, loop cleaning supplies, etc. (there's a lot more I left out) are essential to owning a rebreather. I also bought an extra set of doubles, so I don't have to run to the dive shop so often for fills. Assume that by the time you complete your training, you'll of spent another $500 to $1k more on stuff you need.
That essentialy brings your grand total to approximately $13,500 to $14k or so. the truth is, after I looked back at my credit card statements, it was probably closer to $15,000, but when you've already spent that much money, what's another couple of thousand dollars!
With regards to time, you need to understand that rebreathers are very safe, but only because they require meticulous attention to detail. The entire unit should be systematically disassembled and cleaned, and the loop disinfected, each time it's used. this takes time (aprox. 30 - 45 minutes for me). Assembly, should also be done via a check list, to ensure that no crucial steps are ommitted. The detailed steps are designed to ensure that each critical component is tested for function and accuracy - This should take you approximately 1 hour at first, but you will get quicker as you practice and should be able to complete it in about 30 to 45 minutes on an onging basis. Remember, there are a lot of components that can fail, so one usually assembles at least the day before, which will give you plenty of time to troubleshoot any problems before the dive.
With regard to onging scrubber costs, my unit does not use granular scrubber, it uses Extended Air Cartridges (EAC). Each EAC costs about $30 and is good for approximately 4 hous of use, but that is a subject of great controversy. Furthermore, once you've used one for one or two dives, it's shelf life is limited - I never store mine more than a week, so it's not uncommon for me to throw one away after two dives, if I am not going to or the weather does not permit me to dive the next weekend. I've heard that granular scrubber material will run you about $20 for the 4 hour period, but I'm not the best source to confirm that with. I usually but the cartridges by the 4-pack and that runs me a bit less than $120.
With regards to gas, I am fortunate, my local dive shop, Fill Express (
Fill Express -- Nitrox & Technical Diving Specialist Serving Greater Fort Lauderdale) caters exclusively to rebreather and technical divers. They bank several different nitrox and trimix gases, so it's very convinient. They also have oxygen in banks, so it's very quick to get almost any fill. They charge a flat rate for rebreather fills, which might seem expensive at $20, but it's so fast and convenient, that I absolutely do not mind the cost. However, remember, one fill will last me for approximately 4 hours underwater, so when I go out for a 4 tank dive - no tank switching onboard during the entire trip. There's also the cost of the bailout gases, usually some form of nitrox, but that usually goes for standard nitrox rates or approx. $5 to $6 per fill. I usually never use my bailout, but I do switch the gas to ensure that I have the ideal bailout for the diving I am doing that day.
This is simply a summary of what my experience(s). I encourage you to get feedback from other rebreather users, because all units are different and have different costs associated with them. However, if you're going to buy one, I encourage you to assume that you will always spend more money than you initially thought, because that's usually the case and many of the decisions that you will be making that will cost you $ will usually improve your safety underwater, and how could you ever put a price on that!
Good luck to you and safe diving!