Back-to-school shoppers are planning to buy later this year, spend not more than last year, and do more shopping online - in what may be a harbinger of shopping at year's end.

High gas prices and the attitudes of back-to-school shoppers have some retailers, particularly bricks and mortar types, a bit concerned, writes eMarketer, citing a survey by NPD Group. Most respondents say they'll spend the same (43 percent) or less (21 percent) this year than last. And 51 percent say they'll shop between Aug. 1 and Sept. 1, compared with 56 percent last year.

"In the last three years, back-to-school has been a clear indicator of what's going to happen during the holidays," Marshal Cohen of NPD is quoted as having told CNNMoney.com.

If that's so, a study from PersonalShopper.com may be good news for online retail, according to eMarketer. That study found that some 55 percent of moms are planning to do their back-to-school shopping online this year - an increase of more 25 percent over 2005. Moms point to limited time and money as the reason.