Costco is a great store to buy big and save big. Oftentimes, purchasing in large quantities can lead to tremendous savings—however, sometimes this isn’t the case. As a seasoned Costco shopper, I find the following five items don’t pass my test for good value. I recommend skipping the following items at Costco. You're probably better off purchasing them from a grocer with coupons or at another retailer.

1. Cereal

Honey, you may as well hand me your Abe Lincoln right now. A true couponer knows never to spend over $1.00 for a box of cereal. At $7.99 for a 2- pack, that's $4.00 per bag—well over the "always pay a $1.00 or less for a box of cereal" rule of thumb. Using strategic couponing and store sales, this is a rule that's easy to follow. Most of the cereals sold at Costco are packaged in twin packs and average $7.99.

  • Example:  Honey Bunches of Oats Cereal 2 Pack, 3 lbs. – $7.99

2.  Feminine hygiene products

On average, Costco's prices are almost 50% more than the base sale price at other stores. Here’s an example of what only appears to be a great savings: a large package of 12 boxes of 10-count Tampax tampons at $29.95. That's $0.25 each.

Better deals are out there. Recently, I took advantage of a super saving opportunity on Tampax tampons at Target, sale priced at $3.99 each. Target was advertising a Buy 4, get a $5 Target gift card special on their 18-count boxes. I purchased four using a high-value manufacturer coupon, giving me $2.00 off each box. Final cost? Less than $1.00 a box—only $0.05 per product!

3. Toiletries

Never buy shavers at Costco. A 52-count package of Gillette Custom Plus Disposable Razors for $29.75 may sound like an enticing deal, but really it’s not. Couponers know that high-value shavers and razor deals are always available. More often than not, you can get shavers for as low as free with the right deal.

Other toiletries include shampoo, conditioner and soap. I just bought brand name shampoo, conditioner and hair-smooth spray all for $0.90! I stacked a store sale, took advantage of a store gift card opportunity, and used a manufacturer coupon to save enormously. Rule of thumb for toiletries is to definitely pay less than $1.00.

4. Household cleaners

On average, Costco's household cleaner prices are almost 50% more than the bottom line deal at other stores. Cleaners are always on sale. The smaller the quantity of an item, the larger the savings when using store sales and coupons.

5. Condiments

When you go to Costco, it’s so easy to think about stocking up on condiments, but not so fast. Again, with savings from store sales and manufacturer coupons, items like ketchup, mustard and mayonnaise are far less per ounce than they are at Costco.

  • Example:  Heinz Ketchup Twin Pack, $9.99