BEIJING - A rise in the price of corrugated paper has dampened spirits ahead of Saturday's Singles Day shopping bonanza in China.

According to the China Paper Association, paper prices have risen dramatically since August last year. The price of corrugated paper used in packaging for most goods sold online has increased by more than 2,000 yuan ($300) per ton.

At the end of October, the average price of corrugated paper was about 5,700 yuan per ton, 84 percent more than the same time last year.

Vendors are already feeling the pinch. An online clothes store based in Nanjing, capital of East China's Jiangsu province, used to send out their products in boxes made of corrugated paper to make their garments "appear more high-end," but the gimmick is no longer cost-effective.

"The price of each box has risen from 0.8 yuan to 1.2 yuan," a salesman told the local Xiandai Kuaibao. "It is too much for us, so we have switched to bubble wrap envelopes."

Each envelope costs one yuan, and the price is stable currently, the salesman said. "Most customers only buy one or two items, which can fit into one envelope."

The situation is the same in Yiwu, well known as a production base for small commodities. A vendor there said that in the two months leading up to Singles Day, the store had stocked up paper boxes.

"If the price of the paper boxes keeps rising, we will probably increase the price of our goods," he said.

Nov 11 is known in China as Singles Day because the date, 11-11, resembles four "bare sticks," a term used in China to refer to single people. The day became associated with online shopping with an Alibaba promotional campaign in 2009.

The State Post Bureau predicted the number of packages handled between Nov 11 and 16 will hit 1.5 billion, up 35 percent from the same period a year ago and three times the usual level.

That number of parcels generates a huge market demand for boxes, and vendors of boxes are rubbing their hands in glee. A medium-sized paper box now costs 2.9 yuan in wholesale, 53 percent more than last year, and there is almost no let up in demand.

Meanwhile, delivery companies like ZTO and Yunda, who pack commodities for customers, raised their prices in October, citing the rising cost of packaging. These companies generally charge 5 yuan for a small paper box and 10 yuan for a big one, both 1 yuan more than previously.

Since the price rise, more customers are reportedly packing goods themselves for shipment.

A major logistics platform Cainiao Network said Tuesday that it had begun to recycle paper boxes in hundreds of collection areas in 10 big cities. Tens of millions of paper boxes are expected to be recycled.

Yunda Express, another major courier, said it had already used biodegradable delivery bags instead of plastic bags and recycled delivery boxes in some cities.