This is what you are asking for: https://github.com/JohnDorien1/SysCoin-OfferPriceUpdate
You can define a USD value and set this script up as cron, it will update the SYS price accordingly.
Note it's not having any error handling yet, so if one of the 4 configured exchanges dies it may be faulty.
Consider the tool to be in beta stage!
As for the PGP Keys, I noticed on Linux commandline this is some trouble from time to time with the line breaks, but in the GUI wallet console it's handled correctly.
That's great. I hate how node nests those callbacks, perhaps async could be used to clean up code when adding in some error handling. Regardless, great start. Is the syscoin node library available for download somewhere? I just got into syscoin and the idea of a marketplace inside the block chain is quite intriguing. I may have to set up a mock store just for grins.