Lexpressproperty.com is a real-estate listings aggregator and, as such, the positing of the listing is highly competitive. Sort order was updated time which led customers to update their listings all the time, sometimes even changing as little as dot.
This caused a high load on the server to the constant updates done to the database and this slowed down the website.
I suggested to implement a credit system, where users spend credits to have their listing shown first.
The customer reacted with two potential barriers. Due to the fact the Mauritian market does not use credit cards as much as overseas, the customer and I decided to offer credits for free, depending on the subscription tier of the user, and allow for bulk purchase by bank transfer.
The customer didn't believe this would generate revenue and mainly agreed to limit the endless updates done to listing. But now, this system represents a major part of their revenue.