The RIP software is actually a single suer software license that is purchased with three validations with the printer. As a courtesy to the orginal user the software manufacturer - iProof Systems will provide the original licensee with additional validations of the software at a reduced fee.
When we refurbish a DTG printer and resell it we are also required to purchase a new package to go with the printer.
It is a good idea to do your due diligence when purchasing a used machine from an individual. Questions about software, support, warranty can always be verified by contacting the company that initially sold the machine. That call can also potentially let you know if the machine you are trying to buy is actually owned by the individual or if it is owned by a lease company.
$900 for a RIP software is not a terrible price, a lot of software RIPs are in the $2000-3000 range.