I originally saw it as IOUs (I owe you) although I am not sure how big a business there is in some kind of I owe you network. In a way I like it better as IOus(.)io as a marketplace for io domain names.
I have trouble suggesting a price. From Namebio it appears that IOUS exactly has never sold in any extension. IOU has sold in many extensions, including in io for $282 about a year ago. I think low $$$ is the most this domain name will command, and I don't see it as an easy sale.