Cheap money could be luring builders toward glut territory, Buhl cautioned.

“Despite the optimism ... there is concern of overbuilding. One reason to be cautious is low interest rates. Low-cost debt may be the driving force of new developments, even more so than the demand for those units,” Buhl wrote in his year-end report. “Also of concern is that the majority of new apartment units being delivered today fall in the luxury category, and there are only so many people that can afford them.”

David Dirkschneider, a broker with Price Edwards & Co., saw less cause for caution.

“Demographic and economic trends support a positive outlook for multifamily as more households are renting. Strong job growth will spur new household formation over the next few years as will the progression of ‘echo boomers' into their prime renter years, all of which points to construction activity ramping back up to pre-recession levels,” Dirkschneider wrote in a year-end report.

Sales

Dirkschneider and Buhl both tracked a 10 percent increase in apartment sales — by unit — with the value of properties changing hands at about $290 million last year, more than doubling 2011's sales volume.

The average price per unit on properties with 25 units or more ended 2012 at $60,513, up 94 percent from $31,122 the year before, Buhl reported. Dirkschneider calculated a slightly higher average for last year, $62,687. Investor demand for newer luxury properties drove the average up, they said.

Dirkschneider said the outlook remains bullish for investment sales.

“Transaction activity will continue to escalate this year as out-of-state investors and opportunistic real estate funds target value-added investments, and institutional investors target high-quality, well located assets in core areas,” he wrote, noting that Oklahoma apartments continue to offer better returns than coastal properties.