A merchandising concept barely five years old, giant office-supply chains are spreading across the country. They've already spawned so many stores, they're now muscling in on one another's turf, each claiming to beat the competition's prices to a pulp.

To determine if that's so and by how much, Inc. shopped the catalogs of 10 superstores plus 3 discount mail-order houses, selecting for comparison five identical items. The results are shown in the table below, with stores ranked in order of overall savings on goods. Some observations:

* Savings vary by region. An East Coast purchasing agent could pay 35% more for an item than his or her West Coast counterpart -- and at the same chain!

* Delivery charges are quirky. Most retailers boast free or nearly free delivery; a few add freight charges. All three mail-order companies ship mostly for free.

* The suggested list price, which is referred to when items' discounts are promoted, differs considerably from chain to chain. Not that the figure means very much: even a local mom-and-pop is unlikely to charge full list price, if there really is such a thing. -- Robert A. Mamis

HOW THE DISCOUNTERS MEASURE UP

3-M Post-It Papermate black Texas Instruments Avery copier

Rolodex VIP 3" * 3" pad medium-point calculator with labels Shopping- Dollars off

500-card tray RLP: Flexgrip pen two-color printer 2,310 per box basket RLP of % of RLP

Retailer/location RLP*: $18.25 $12.84/12 RLP: $13.08/12 RLP: $85.00 RLP: $42.73 total $171.90 (discount)

Office Club/L.A. $9.49 $5.69 $5.19 $39.99 $27.99 $88.35 $83.55 48.6%

Office Club/Seattle 10.99 5.59 5.19 39.99 27.99 89.75 82.15 47.8

Staples/L.A. 10.59 5.99 5.26 39.99 29.59 91.42 80.48 46.8

Bizmart/St. Louis, 9.94 6.69 6.99 44.99 30.51 99.12 72.78 42.3

Houston

Office Depot/Houston 10.61 5.77 7.36 45.97 30.46 100.17 71.73 41.7

Office Depot/Atlanta 10.61 6.72 7.36 46.97 30.46 102.12 69.78 40.6

Quill (mail order; 11.88 6.99 6.68 49.88 27.99 103.42 68.48 39.8

708-634-5708)

Staples/D.C. 11.88 6.07 7.49 51.29 29.59 106.32 65.58 38.2

Staples/Boston 11.88 6.39 7.49 53.99 29.59 109.34 62.56 36.4

OfficeMax/Milwaukee 12.64 7.29 7.96 49.82 31.99 109.70 62.20 36.2

Arvey Paper/Chicago 14.49 7.08 8.52 58.99 34.18 123.26 48.64 28.3

Reliable (mail order; 14.75 9.99 9.96 59.96 38.96 133.62 38.28 22.3

800-735-4000)

Viking (mail order; 16.07 11.67 11.16 59.99 42.58 141.47 30.43 17.7

800-421-1222)

Note: prices taken from catalogs current as of March 1, 1991.* RLP indicates a representative list price. n -- Researched by Susan Greco