When I hear NetSuite ads, it's only while listening to the absolute dumbest sports talk shows. Apparently this marketing works...
Contrary to what people might think, companies are not ran as military with the CEO being a commander-in-chief. In most of the companies, members of the C-suite have a certain or total autonomy to make any decisions that they want as long as it is somewhat within their domain. The conflicts between them are resolved via negotiation and horse trading. Just because the CIO does not like what the CFO is doing, does not mean that the CFO is wrong in making that decision, same as just because the CFO does not like what the CIO is doing does not mean that the CIO is wrong. When one CxO steps on feet of another CxO it is either resolved by reaching a new agreement going forward or resolution is punted into the future or one of the CxOs leaves.
If your company really does have a purchasing proces so rigorous that it will reject an "IT" contract signed by the CFO despite it being within their purchasing limit, then there's a reason for that. The reason typically being that in the past there was enough naughtiness by some CxO that they went to all the trouble of putting some heavy bondage into their purchasing rules.
Also, I would be willing to make a cash-money bet that CxOs shopping outside their domain authority don't get immediately fired for that. Even at your company.