I have a new 40 gallon Rheem on one side of the house and a tankless on the other side. One of the posts mentioned that the insides are all about the same, which is true, the price varies with the warranty which is either 6, 9 or 12 years. You can get a nice electric GE or Rheem (GE is Rheem) 40 Gallon for under $300 with a 9 year and under $500 for the 50 gallon. The only real difference between the 6 and the 9 is element wattage. My 40 gallon is new because The little ball valve snapped off in the "open" position when I was draining it, which after 16 1/2 years is the only thing I have ever needed to do even here in Florida on really "scaly" water. Changing the fittings and the anodes are "feel good" fixes for the few dollars but really are not necessary in the overall picture. If you spent $500 for the tank and had it for 10 years the cost is only $4.16 a month and only $2.60 if it makes it to the 16 year mark. Considering what it does....buy a new one!! Now for the other side, tankless. I have a garden tub in the master and it takes more than a 40 gallon tank to fill it with hot water. After a ton of research, BTW...I have had the tankless for 9 years now, and they are all over the place in quality and cost. The 2 biggest factors in deciding which one is average incoming water temp and size. Once that has been determined, the guts of the thing need to be sorted out. The basic models have an incoming sensor to turn on the elements and outgoing to turn them off. The more expensive models will have multiple heating chambers with multiple sensors that will vary turning them on by incoming water temp and smooth out the process to keep the temp even. A whole house computer controlled model should be under $1K, anything more and you are into commercial level or have a mansion with 5 or more bathrooms. If you go with a multichamber model, look at the elements and make sure they are common hardware store variety for easy replacement. They usually are spa heater elements. The sensors are the screw-in type and should also be common. The higher end models will contain a circuit board which as any electronics are prone to failure, just make sure that you are dealing with a reputable company that will be around for awhile. Those boards are full of electronic relays. I have had to exchange my circuit board once in 9 years and no elements and one sensor. The board exchange was around $150. the sensor less than $10. These things take a lot of power to hook them up so if you are replacing a tank model you will have to add on several new breakers and wire from the box. They take up very little room and you are never without hot water as long as you have power or gas. I have a Siesco whole house unit that cost under $600 9 years ago and I would not trade it for any amount of money. Some of you will ask why I have both, and the answer is that I am very rural and we do have a lot of power outages, The tank unit can be powered by my backup gen set but the tankless can't, mainly because of the size of my gen set (8K). I could do it if it was the only thing I was running but that is another discussion. Hope this helps! enough of you guys have helped me on my bike stuff!