Records were still being set last month at New York's art sales, as the £17.2m sale of a Lucian Freud painting demonstrated, yet the commercial art world is undeniably jittery.

While some noted that sales totals were down - by $200m in the impressionist/modern category - others started to turn their attention to the art fair phenomenon.

Last month there were at least six - in Cologne, Mexico, Sao Paulo, Brussels, Vienna, Chicago - in the weeks between the Armory Show and Art Basel.

Former Guggenheim director Lisa Dennison may have been right when she said that fairs were the new biennales, but like the 200-plus biennales, many are starting to think the fair phenomenon is out of hand.

The buyers appear to agree. Tate staff, no doubt busy with their Latin American collecting, reportedly made a showing in Mexico, but at many fairs, sales appear at best to be levelling off, while others are giving up entirely. Of course, dealers make attendance decisions on a commercial basis.

But what about museums? The whole thing may seem laughable to curators fighting local authority grant restrictions, yet fairs remain useful places - just as biennales are still important for the chance to see work by a lot of artists in one place.

Nevertheless, choices have to be made. With Basel hotels sold out months ago, thanks to an ill-timed European cup match, for UK curators that means Frieze and its increasingly popular satellite Zoo. For once, as museums save up their precious travel budgets, they have the consolation of knowing that for the first time in years, they are not alone.

Jane Morris is an arts journalist and editor