Amazon.com (NASDAQ:AMZN) has made shopping so easy for customers, specifically Prime members, that many simply reflexively route purchases through the site.

When you can buy pretty much anything with a couple of clicks and it arrives two days later through no-cost shipping, it's almost silly not to. Because the online retailer has excellent or at least competitive prices for so many things, few people pause before exercising the right to buy granted by their $99-a-year Prime membership. The same can be said of regular shoppers who opt to not pay for Prime but still consider Amazon a go-to, low-cost shopping resource.

Amazon, though it's often a good choice for consumers, is not always the best one. It's a great company to buy many things from, but there are items to avoid and other retailers that offer better deals on certain products. Savings.com, through its PriceJump browser plug-in and app, compared Amazon prices on 1,500 items costing more than $10 with prices elsewhere on the Web one day last year, and found that the company had the lowest price about half of the time, MarketWatch reported.

That's pretty impressive when you consider that the app compares Amazon's prices to more than 5,000 other retailers, but it does show that there are clearly some items to buy elsewhere. Of course, pricing is fluid and a bad deal on Amazon today could be replaced by an excellent tomorrow. But with that caveat, here's a look at some items to avoid from the online retailer.

Electronic items over $100
This is not a hard-and-fast rule, but in a broad sense, shoppers should be wary buying anything that costs over $100 on Amazon.

"On purchases over $100, PriceJump beat Amazon's prices 70% of the time, with an average savings of $70.00," Savings.com said in a July, 2014 press release. "Savings were even higher in the Electronics and Photography categories."

That's not to say that Amazon does not have deals on big-ticket items. It sometimes has great prices on electronics and other pricier things, but buyers should be wary and check prices versus other retailers when ordering anything above the $100 threshold.

Be careful with clothing
Amazon sells just about everything including clothing but it's not always the best deal in this category and you have to factor in the inability to try things on. The site does have a liberal, easy-return policy, but it still takes more time and effort than simply picking another size from a store shelf before buying.

"Amazon is not the greatest place to shop for clothes and shoes," CouponPal.com spokesperson Erin Konrad told MarketWatch. "Most of the brand names you can find on Amazon (like Anne Klein, Vince Camuto, Nine West) are available at other retailers (Nordstrom, Luisaviaroma, etc.) that offer promotions that will save you money."

Avoid mattresses
If buying clothing without trying it on and then having to return it sounds like a hassle, imagine having to bring a king-size mattress from your door to your bedroom only to decide it's not comfortable and needs to go back. Amazon can be price competitive with other mattress retailers, but its shipping is lacking compared to local and even national bed-specific brands, which handle in-house setup and even removal of old mattresses in some cases.

This isn't a question of price (though there are often better deals to be had than can be found on Amazon) -- it's one of common sense and convenience.

Amazon Mattressjpg

This mattress may or may not be a good deal, but if you don't like it. returns can be a hassle. Source: Amazon.

Third-party grocery items
In addition to the millions of items Amazon stocks in its own warehouses, it also offers millions more through third-party sellers, which do their own shipping. These items generally come with a shipping charge (sometimes a hefty one) and the prices -- specifically on food and grocery products -- can often be higher than those offered in local stores. In addition, in some cases, the quantity in which some grocery products are sold is much larger than what would normally be needed (or wanted).

Once again, this can vary and there are some excellent deals on third-party food items. In general, however, the more specialized something is, the more of a markup you can expect to pay. 

For example, I regularly purchase a popular brand of gluten-free baguette locally but have been forced to buy the product on Amazon when my nearby store has been out of stock. The online retailer carries them but at a hefty markup in quantities of two packages at a time with an added shipping fee. 

That's just one anecdotal example, but this is an area to be very wary of, especially when you factor in shipping charges.

Daniel Kline has no position in any stocks mentioned. He is currently shopping for multiple mattresses. The Motley Fool recommends and owns shares of Amazon.com. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.