To reduce the wait time for hot water in your units that are far from the water heater, consider installing a recirculating hot water system. This system keeps hot water readily available at the taps by continuously circulating it through the pipes.
The cost for a recirculating system typically ranges from $200 to $800 for the unit itself, with installation costs varying between $100 and $300, depending on your local labor rates. In larger cities, these costs may be on the higher end.
Another option is to install point-of-use water heaters, which are smaller units placed closer to the faucets or showers. These typically cost between $150 and $500, plus installation.
For both options, it's advisable to hire a licensed plumber or HVAC professional to ensure proper installation and compliance with local codes.
As a next step, I recommend getting 2-3 local quotes on Handyman.com to compare costs and find the best solution for your situation.
— Assisted answer