That £110 million or £150 million, if the guy was telling the truth, is the cost of the 3 phases of the development. Phase 3 hasn't even started yet which is Taxiway Foxtrot, the extension to Taxiway Alpha, to get it closer to the end of runway 26 and the conversion and expansion of the Signature stands by the former flying club.
If you think that Luton suffers from a lack of bizjet stands just wait until 2019 when those stands go back to the airport.
The new multistory is not part of the existing development so will be funded separately or as part of the DART link.