Partly based on a fear of getting their art and antiques "burned" by overexposure on the auction market, sellers increasingly are turning toward private sales, reports Barron's.

Auction houses have seen a dramatic rise in private treaty sales, behind-the-scenes transactions that take place out of the limelight of public auctions, and many collectors still turn to galleries for more specialized, discreet sales.

Often reserved for special clients, private sales earned Christie's $808.6 million in 2011, which represents 14 percent of its $5.7 billion revenues, and a 44 percent increase in private treaty sales over 2010. 

Similarly, Sotheby's did $814.6 million in private treaty sales in 2011, a 65 percent increase over the preceding year.

The world's third largest auction house, Dallas-based Heritage Auctions, recently brokered a $850,000 private sale of a Batman comic, part of a small but growing revenue stream in this house's overall $850-million in yearly sales.

Outside of the auction arena, collectors traditionally have turned to galleries for private sales. High-level dealers are often experts in their field who market to a select clientele with whom they maintain relationships.