TLDR; How much would a custom mobile number cost?
In Switzerland, you can buy custom mobile numbers starting with 079 or 075. As with other issued numbers (e.g. license plates for cars), some combinations of numbers are more popular than others.
But what exactly makes a number "special", simple or memorable? Swisscom introduces categories (or "classes") with certain prices, the simpler the number, the more you pay for it. You can have a look at the whole table here: Einfache Rufnummer.
The script above recognizes the categories and shows the matching price.