Costco's shoppers are familiar with the big box stores' low prices, but one shopping expert warns there are some groceries that shoppers may be better off buying at a local supermarket.

While $5 rotisserie chicken and $1.50 hot dogs are among the famed bargains offered by Costco, food writer Su-Jit Lin, who is a self-professed fan of the wholesale club, writes in an article for Eating Well that the warehouses have some food items that aren’t the best deals if you don’t have to buy in bulk.

Lin writes that shoppers can "shave nearly half a dollar on a gallon of milk" at other stores. While Costco offers milk at $4 a gallon, she says the dairy product can typically be purchased for less than $3 at Lidl, Aldi or Target.

Sandwich bread is another item that can often be found with better deals at a local supermarket, according to Lin. Instead of buying Costco’s double-packs of sandwich bread loaves, Lin suggests checking a local Publix or Krogers for their "buy one, get one" specials on premium bread brands.

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"And you don’t actually need to buy two loaves to get the half-off deal, saving you money and the stress of trying to find space in your freezer before any mold appears," Lin writes.

Super-sized bagged salad kits at Costco can run between $7 to $9, according to Lin, while kits in smaller sizes can be found on sale at Kroger, Publix, Sprouts and Lidl for between $2.75 to $3.50.

Raw chicken is another item that Lin says can be found for slightly cheaper at other supermarkets. At $3 a pound for breast or thighs at Costco, Lin says she has found family packs of chicken breasts for as low as $1.79 a pound at other major supermarkets.

Depending on how often they’re used, herbs and spices might be a better buy in sizes smaller than the larger tubs from Costco, according to Lin. The Eating Well Test Kitchen says ground spices are best used within a year to avoid losing their color, aroma and flavor.

Stocking up on canned soup can be better for your wallet at local supermarkets, where the product can go on sale for three for $5, and sometimes less, and allow shoppers to get a mix of flavors, Lin says.

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Large bags of cereal at Costco can sell between $7 to $14, whereas supermarkets rotate which major cereal brands go on sale and also offer coupons for an even steeper discount, according to Lin.

"I’ve used this multi-savings method to get name-brand cereals for $1.50 a box with the purchase of six boxes," Lin writes.

Despite the potential savings, Lin encouraged shoppers not to fret over planning their shopping trips.

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"If you’re already at Costco and need one of the things on this list but don’t want to go to another store, of course you should just buy it while you’re there – no need to make a special trip," the expert says.