Not sure why it was broken (other than my on-going efforts to remove old code that is not PHP7 compatible, and also a recent fix of a security vulnerability) but the for sale page works again. (I thank an alert and patient buyer who, instead of moving on, took the trouble to notify me.) Enjoy browsing, and please do let me know if you are looking for something specific, as I have many calculators not visible here, as I have not yet ascertained their condition, made pictures, or set a price.