VistaJet, which is known for its distinctive silver planes whose usage often costs around 10,000 euros (7,962.86 pound) an hour, is close to appointing financial advisers and could start a sale process in September, one of the sources said.

A VistaJet spokeswoman said the company's multi-millionaire founder Thomas Flohr had stated in many recent interviews that he had no plans to sell and that for the time being the company is not for sale.

Flohr, who bought his first plane in 2003 and oversaw VistaJet's maiden flight in 2004, now runs a fleet some 40 strong and says he is the biggest business jet customer of Canadian planemaker Bombardier Inc.

VistaJet's 100 percent owner, Flohr is a former finance executive more likely to be found wearing jeans than a suit and who was once married to Katharina Flohr, creative director of jewellery maker Fabergé and a founding editor of the Russian edition of fashion magazine Vogue.

Their daughter Nina, currently a brand director at VistaJet, was charged with revamping its management while a teenager. Since then VistaJet has boosted its image with moves such as splashing graffiti across the tail fin of one of its jets.

LIKELY BUYERS

Valuations for the sector are hard to come by, as the firms involved are largely privately-owned. But Bombardier last year sold FlexJet for $195 million in a deal estimated by analysts to be worth between 8 and 9 times core earnings (EBITDA).

VistaJet has core earnings of around $100 million, one of the sources said, giving a deal value of up to $900 million at those multiples.

Private equity firms are the most likely buyers of the company, the sources said. One said the firm, which caters for rich clients ranging from Russian oligarchs to Chinese entrepreneurs, could make for an attractive trophy asset.

VistaJet reported a 25 percent rise in 2012 revenue to around $400 million and the spokeswoman said it had grown at a rate of 25 percent for the past two to three years - a potentially attractive rate for a private equity firm in a market short of primary deals.

The company shares a sector dominated by U.S. peers such as Warren Buffett's NetJets [BRKNT.UL], which pioneered the "fractional" ownership model in the United States in the 1980s, where clients buy a share of a plane in return for guaranteed access for a fixed number of hours or days in a year.

By contrast, VistaJet, which owns all its aircraft, allows customers to purchase flights by the hour without taking a stake in the plane.

(Editing by Jane Merriman and David Holmes)

By Freya Berry and Pamela Barbaglia