By Slash Lane

Published: 10:00 AM EST

Investment bank Piper Jaffray said Thursday that weakness in consumer spending will bite into PC sales next year, including Apple's, leading the firm to cut its 2009 sales estimates for the Mac maker along with the broader market.

Although there's no evidence to suggest that Mac sales have slowed thus far, analyst Gene Munster cited "low visibility" into next year's environment as reason to adopt a conservative approach and model Mac sales growth to drop from 43% year-over-year in 2008 to 10% year-over-year in 2009.

"The primary reason for our universe-wide estimate cuts is that the economic and consumer spending outlook has deteriorated significantly over the last month, which we expect to continue through 2009," he wrote in a note to clients.

Apple has seen its Mac sales grow at approximately 2.5 times the industry average for the better part of this year, but that rate is likely to contract to approximately 2 times the industry average next year, the analyst added.

As such, Munster reduced his 2009 calendar year revenue estimate on the Cupertino-based company by 5%, modeling overall revenues to be up approximately 25% for the year compared to his previous estimate of 32%.

"Our reduction is primarily driven by macroeconomic headwinds causing overall PC sales to grow at about 5% year-over-year in 2909," he wrote. "We believe Macs will continue to gain share, but we are reducing our year-over-year growth to 10%, down from 16% previously."

Specifically, the analyst expects Apple to generate 2009 calendar year revenues of $41.22 billion on sales of 11 million Macs, 45 million iPhones, and 41.2 million iPods.

He continues to recommend that investors Buy shares of Apple, but lowered his 12-month price target from $250 to $235.