Can "shop" (related to selling or stores) be used as a transitive verb?

There is an idiom to shop (something) around which means, more or less, to present (something) to a variety of potential buyers to see who will make the best offer for purchase. The example given, “to shop Teixeira” is just a truncated version of this idiom, dropping the around.

Some examples of this idiom from COCA:

• But how serious could he have been about leaving Sacramento if he didn't have a high-profile agent to shop him around the league, someone who might have bullied or bluff-ed the Kings into talling sign-and-trade with other teams?
• For a fee, his company will build a prototype and shop it around. If a corporation bites, Davison shares royalties with inventors.
• They get a good idea, shop it around, raise some capital, then sell it off to a bigger company
• Insurers sometimes shop patients around to a series of IMEs, flying them out of state and putting them up at motels.
• And how do you know if you're getting a fair shake? # " I always tell people to shop it around, " said Nedler. " Take it two or three places. You have to trust who you're dealing with.

The shortened version seems commonly used in a sports context:

• In fact, with the trade deadline coming up Monday, the Bears ought to shop him now and try to retrieve something in return.
• The idea, they said, was to be up front with free agent Monk during a time when he also could shop himself to the highest NFL bidder.

This truncated version possibly developed from cases like the first example above (shop him around the league), where the phrasal verb to shop ___ around was reanalyzed as a normal transitive verb to shop ___ that takes an optional prepositional phrase with around—as in around the league. Notice that the example shop patients around to a series of IMEs uses “around to”, which is what you’d expect with a phrasal verb.

This idiom is not the same idiom as to shop (a business) or to shop (a selection of products), which is what the other examples are. People definitely use shop in this way. Here are a few examples of this in COCA:

• Draw up a grocery list for the " big " holiday meal before you go shopping. Divide the list by section and shop the store in that order.
• Sam's Club stores are huge and carry not only electronics, but everything from auto accessories to food to pharmaceuticals... But: You may need to shop the store repeatedly to recoup the $35 annual membership fee.
• " We shop the farmers markets for amazing things like raw dates on the stem, red burgundy okra, romanesco, and saturn peaches, " says Holly Vesecky of Holly Flora in Los Angeles.
• I am a die hard fashionista and, you know, I shop the sales.
• Before he could ink a deal, he was automatically switched to TXU Energy... His price jumped 71 percent overnight, to 18.8 cents a kilowatt hour from 11 cents. " No way was I going to pay that, " says Mr. Dreese. He was able to shop the market and switch to another retailer for 13.3 cents a kilowatt hour.

To me, this idiom to shop ___ is different from to shop at ___ because it implies a slightly more intense sense of intention to the shopping.

It's certainly not standard English to Shop Walmart, for example. Any such usage is probably down to either 'marketese' or the specialised vocabulary of the [baseball, etc.] sports transfer market and sports writers reporting thereof.

But you can certainly say We shopped for ski accessories, and countless people will have said We shopped till we dropped.

The usage OP is asking about seems to come down to whether shop can normally replace buy [from], and the answer is it can't. Also it can't grammatically replace sell, or offer for sale except in the baseball player example - and I don't look to sports writers to tell me what's valid English for general use.

The use of "shop" as a transitive verb implies the preposition. "To shop Teixeira" is equivalent to "to shop out Teixeira", a slightly slang term for "to offer Teixeira's services" as in to sell his contract. "To shop Walmart" is understood as "to shop at Walmart", while "to shop shoes" is "to shop for shoes".

So grammatically, "shop" is not a transitive verb; it requires a preposition. However, colloquially it can be understood as such, and thus it may eventually become "official" over time as it passes into common usage. Such is the fluidity and organic quality of language.