The least expensive 529 college savings plans available nationwide are offered by Ohio, Illinois and North Carolina, a research firm reports.

The study by Savingforcollege.com LLC, Rochester, N.Y., looked at direct-sold 529 college-savings plans from 49 states and the District of Columbia.

Savingforcollege.com’s 529 Fee Comparison Study did not include plans sold through financial advisors because of their complicated fee structures, the company says.

“There’s been a huge effort on the part of the states and their outside vendors to bring down investor costs in 529 plans,” remarked Joseph Hurley, founder of Savingforcollege.com, a division of Bankrate Inc., New York.

Fees and expenses can have a significant impact on a college savings fund, Hurley notes. He warns, however, that fees are not the only factor in selecting a particular 529 plan. “The more important figure is the net performance of your 529 account after all costs,” Hurley says. “I might pay more if I felt I could get better net returns without taking on more investment risk.” State taxes and other benefits are also important factors.