Anna,
I have similar units to Heybud's son, I think, ours are about $50 to $150 dollars each, depending on the kw rating. Do an internet search for them, German and Japanese manufacturers both make good stuff, not just in the US and look for 220v. US units are huge, all you want is a heater at each location, small, quick and inexpensive. Then mate that with a solar water heating system. In summer you will not need the tankless heater or if you do it will be at a minimum and in the winter when the solar is struggling the tankless will be your best friend. Bath tub is the biggest obstacle for the instant heaters.
