I think the idea of electrical prices has a lot to do with where you live.

In Socal where it is about 24 cents a KW, then costs are huge. In much of Canada where costs are 6 cents a KW, then so much of an issue.

Supermarin 300 is rated to 1100 gallons... I don't know where Richard (Salty Supply) got that rating, but that's the one for the SM250 on his site.