I think my water heater is going out. My house doesn't have natural gas, so I'm stuck with electric. I didn't realize they had tankless electric water heaters before now. Has anyone used one of these? They are not much more than the regular ones.

https://www.homedepot.com/p/Rheem-Performance-27-kw-Self-Modulating-5-3-GPM-Electric-Tankless-Water-Heater-RETEX-27/300800755

The water heater is not the expensive part. Note that you need THREE 40A breakers and you will need very large gauge wires from your breaker box to the water heater. You can't just hook this up to the existing wiring for you conventional electric tank-type water heater. You will need an electrician to install that. I also HIGHLY recommend that you have a water softener to eliminate scale. That said, I have one of these for my lake cabin and it works pretty good and is much more economical than a standard water heater.

Don't go electric tankless, not reliable, problematic, and expensive to run

He's stuck with elec tankless or elec tank. You need to do some research and determine what's best for you. If you have >4 in your house and want to run showers and washing machine, dishwasher etc all at the same time get a tank-type. If you have only two of you at home or are willing to coordinate use of hot water than a tankless might be better. If you travel a lot and don't use much hot water than tankless looks even better. I have a cabin with one bathroom and I'm not there full time. It's absolutely more efficient than a tank water heater for my application. The cost of retrofitting could be prohibitive in your situation, as I pointed out. Several factors to consider.

Thanks for the info. I didn't realize it would need additional work to install. I'll just stick with a tank for now.

Electric tankless will require beefier electric. I have 3 of them. If you have a decent electricity price then they are economical. They last just as long as any other tankless and they are far more efficient than gas.

Mine all require two 40A or larger circuits.