Monarch are buying their 737s through a "sale lease back scheme". This where the airline negotiates the aircraft price but a third party actually buys them (in this case Boeings Air Lease Corporation) and the Airline then leases them back, so Monarch will be paying no money up front for these planes! This is how 90% of all Airlines buy their aircraft party because it totally removes the Aircraft debt from the balance sheet, which would be vital to an asset poor company like Monarch.
The link between Greybull and Montegazza is very tenuous, lots of rumours but no proven link between them. Greybull are a perfectly legitimate investment company and Monarch a viable business (the days of money laundering are long gone)!