When dealers who do not enjoy the high profile of professionals long established on the international scene also sell hand over fist, this confirms that genuine collectors are calling the shots — investors and speculators instinctively turn to famous galleries. Salomon Lilian, an up-and-coming Amsterdam dealer who looks set to become one day the new Robert Noortman of the Dutch trade, shares Van Haeften’s willingness to make clients benefit from his luck when he buys cheaply. He too had a stunning masterpiece that was modestly priced, at €300,000 ($387,000). This time, though, it was the work of a major Dutch master, Jan van Goyen. The marine on panel with a sailing boat bending in a gale-force wind over choppy waters is painted with a freedom and lightness of touch in the brushwork that gives it the feel of a study from nature, as if the painter had set up his easel at the edge of the sea. Here again, the price struck me as very low, even if Lilian insists that this partly reflects the austere character of the composition, all in shades of brown. At the time of writing, a university museum in the American Midwest that had requested the picture be sent for approval by the trustees was working hard to muster the funds.

As elsewhere, rarity proved a powerful selling point. Lilian displayed one of the largest still lifes on record, by Balthasar van der Ast. By now the €750,000 ($966,000) picture must be hanging in a Dutch collector’s home.

Here and there, price corrections were made, slightly reducing the price inflation of the past three years.

Lilian tells a revealing story about a fine winter landscape done around 1640 by Aaert van der Neer. Skating townsmen are playing the ancient game of kolf, with sticks resembling those of modern golf, on a vast expanse of frozen water. When I saw it hours before the private viewing, the picture rang a bell. Yes, Lilian confirmed two days later, he already had it on consignment in 2008. The price then was in the region of €550,000 ($708,000). The owner now really wanted to sell it and had cut down his ambitions by 20 percent. That same day, a German collector who had yearned for the picture in 2008 and had found it too expensive gleefully bought the desired picture.

Indeed, a factor that contributed to the overall success of Old Masters at Maastricht this year was the sprinkling of extremely good pictures at the bottom tier of the price scale, including masterpieces of museum quality.

Rafael Valls, whose London gallery on Duke Street is a few steps away from Van Haeften’s, had laid hands on three pure gems. One was a bold still life in an unusual, highly personal style. Each of the carefully selected flowers rising out of a vase is handled in a sculptural fashion that gives the small panel a striking monumentality. The consummate skill adds to the mystery of an artist whose signature, "C. van der Radt," was previously known from just one other picture, a genre scene dated 1676.

Two other interior scenes are related to van der Radt’s 1676 picture, and that is as much as is known about the oeuvre of the artist whose name does not appear in the records of any of the Dutch guilds. Since membership was mandatory for painters intending to exercise their activity as professionals, the conclusion must be that he was a wealthy man indulging in a private passion. This might explain how such a brilliant artist came to fall under the radar of his contemporaries and of succeeding generations of art historians. The laughable €95,000 ($122,000) price tag, which reflects the painter’s obscurity, hardly does justice to his mastery. At three times that figure, the van der Radt would still be worth a go. It left the stand on the opening day.

If anything beat the still life among the works offered by Valls, it was the view of a church interior signed and dated 1640 by Anthonie de Lorme. Light falls from an invisible source high up in a dome and runs down the classical piers that support it. Tiny characters standing in the middle look up as if struck by some astonishing sight. In mint condition, the panel, 11 inches long, had a €19,000 ($25,000) price tag.

I happened to be there when a New World museum curator approached and closely peered at the panel. The art historian slowly edged away, came back to take another close look, inquired a second time about the price, and as the dealer made it clear that he was prepared to come down a bit, settled for it. This was for his personal collection, the curator volunteered. A fraction too small and too understated to justify display in a major museum, the de Lorme easily qualifies as the bargain of the month as Old Master paintings go.