Unlike most retailers in the down economy, Ken Spriggs is having a hard time keeping his shelves stocked during the back-to-school shopping season.

Binders, backpacks, notebooks, staplers, alarm clocks and other supplies are all here one day, gone the next. Racks with hundreds of articles of clothing are rolled out onto the sales floor every hour, and entire pallets of paper are scooped up by shoppers in the blink of an eye.

"Sales have been really robust," he said. "There's definitely a rapid flow of merchandise."

Though it might seem as if Mr. Spriggs is living in some post-recession retail fantasy, he actually is firmly grounded in the reality of the downturn.

As manager of Cranberry's Goodwill store, he's seen firsthand how the economy has affected consumers, who are turning away from malls and office supply stores and heading instead to such thrift shops as his.

"People are realizing they can't afford to go and spend the way they have in the past," he said. "We've filled a niche in hard economic times."

He's not alone in reporting the trend. As families approach the start of classes with tighter budgets, many nonprofit stores that sell items for pennies on the dollar are seeing increased demand for back-to-school items. In response, they're conducting backpack and clothing drives, and soliciting donations to meet the increased need.

Red White & Blue Thrift Store in Bellevue is getting 350 to 500 more customers per week than last year at this time, a manager said. The store, which runs strictly off donations, prices an average piece of children's clothing at $2.95 and school supplies at 95 cents.

Linda Widmer, manager of West Mifflin's Salvation Army store, also has seen more shoppers looking for back-to-school bargains. The store stocks clothing, book bags, shoes and office supplies, which customers are buying rapidly.

"They can't afford the new stuff," she said.

Huntingdon Bank's annual Backpack Index shows how expensive paying for school supplies and events can be.

To develop the index, the Columbus, Ohio, bank computed the costs of extracurricular activities and standardized tests; aggregated shopping lists from 25 schools in five states that the bank operates in, including Pennsylvania; and searched Staples.com for moderately priced items "to replicate the way people would actually shop," said spokeswoman Maureen Brown.

The index found that between 2007 and this year, the cost of sending an elementary student to school shot up 34 percent, from $351 to $472. For high school students, the cost increased 11 percent, from $894 to $998, and for middle schoolers, the price remained relatively stable at $535.

Despite the effort to craft a realistic, moderate estimate, "A lot of parents actually told us, 'This is underestimated. It's actually much more expensive,' " said Ms. Brown.

In a recession, those expenses can be all the more painful.

According to the National Retail Federation's 2009 consumer survey, families are expected to spend, on average, 7.7 percent less this year on back-to-school shopping than they did last year due to the economy.

Fifty-six percent of respondents said they would hunt for sales more often, 49.6 percent are planning to spend less overall, 41.7 percent are purchasing more store brand/generic products and 40 percent are planning to increase their use of coupons.

For thrift stores, that penny-pinching can be a boon. The Goodwill store in Cranberry prices shoes and clothing at $1.99 and binders at 99 cents.

"They're quality goods, but without the inflated, exorbitant prices," said Mr. Spriggs.

And because deals are only good as long as they last, charities are launching efforts to encourage more donations.

Last week, Salvation Army in conjunction with Huntingdon Bank donated 1,000 backpacks filled with school supplies to local schoolchildren. The bank also donated 13,000 more throughout its operating area. It was the first time the two joined forces on such an effort.

Meanwhile, Goodwill for Southwestern Pennsylvania has been distributing fliers in its stores to advertise its first-ever, back-to-school clothing drive in August and September.

"There have been points when donations have been very low, and we've called on the community to help," Mr. Tobiczyk said. "What's different now is that donations are not particularly low, but demand has increased so much that we have to rely on the public to fill that need."