Advice on 120G WH replacement

Our 12 year old 120G Ruud Pacemaker electric heater has started leaking, just before we are getting ready to put our property on the market. Plumber confirmed that the tank is corroded and has a slow leak and can't be fixed. The plumber offered to install a 50G electric for $1,000 as a replacement, and said that is all they have to offer. I said no, on account of our house having 4 bathtubs (3 master bedrooms + guest furo) - 50G would never be enough.

I contacted another plumbing company and their recommended proposal is a 80G heat pump WH for $4,500 (total with installation) that comes with a tempering valve to increase its output to similar of our old 120G. We live in Hawaii, so heat pump technology would be a good choice. As an option they also offered to install Solar instead for $7,500. They also said 80-120G electric ones are no longer available as an option, and they will not do that since they are licensed plumbers.

I am quite certain that the $4,500 proposal will work well for our situation once installed - all tubs aren't used at the same time, and 80G should be enough to run a few showers at the same time.

Do we have any other options?

We do not have gas, so that is not an option for any type of heater.

A large capacity Tank-less would likely require rewiring and upgrading our electrical system, so that would be pricey as well, on top of the actual system. I suspect at least close to 4,500 total, if not more considering going through walls.

Point-of-use installation is not a viable option because we have a total of 4 tubs, 5 showers and 9 sinks. All plumbing is inside walls with no pipes readily accessible.

I see larger commercial heaters are available (at least online). Is that possible to install in a residence or would that cause problems? The laundry room could fit up to 32" diameter tank. Is it even allowed? I am not quite sure if that would actually be cheaper though. The $4,500 Heat Pump proposal is actually priced at $2,500 (online, from mainland), so I'm assuming the added $2,000 is shipping, hauling, installation, connections, removal, profit, etc. Those costs would likely be similar for a commercial heater and they seem to be priced around the same.

Multiple smaller heaters could be an option but would require additional space and remodeling.

Any opinions are welcome. I am leaning towards accepting the proposal, but I just want some confirmation that it is reasonable.

Thank you.

80 gallon HTP electric heater with 4500 watt elements is still sold as light duty commercial when installed in a house you can get a life time warranty on tank it is made in Massachusetts
With shipping to Hawaii should be installed around $3000 I would think

Thanks for the input - it did make me look for other options, and I thought I should follow up now that I have had the install done. I did go with an 80G hybrid with a similar output to our original 120G, and I did find it cheaper - I am still not sure exactly how much it will cost me, because I am waiting for a partial refund. - but in the mid two thousands, which is more reasonable than $4,500.

The plumber did find something "interesting" when he switched out the heater though. The old T/P pipe leads into the wall, and then comes out of the wall a few feet away, and is simply capped there, likely because they found no convenient way to drain it anywhere.

So now I'm contacting the plumber who did the original installation of the pipes in the house and wondering why they put a potential bomb in our laundry room. I suspect they will come back and address that issue.

Put the house on the market and provide a $1000 credit towards a new tank.

Yeah, we did consider leaving it up to the next owner to decide.

But since we are still living in the house and, selling it may take anywhere from a few months to a year, so I think we prefer having a functioning water heater.