Ex-Mil aircraft are classed as "Type II" in EASA-land and have special regulations appended to them.
Because they don't have EASA/FAA Type Certificates most fly under a "Permit to Fly" and have restrictive maintenance programmes normally ensuring that they are maintained more stringently than when in 'Service'.
Even if no Type Certificate - a Type Course may still be "required" - for the Vulcan, Marshall's had to re-create type courses for its Certifiers.
Additional restrictions are made against Turbine engines due to their complexity.
You will probably need Part 145 maintenance and Part M Management for it too, not forgetting OEM support for both the airframe and Engine to ensure stresses and repairs are properly overseen.
All adds up to quite expensive support costs on top of quite cheap purchase costs (I think the real purpose of these reg's is to price-out the ex-mil market)