"I can't sell it you," is a very rare form. It is used by a small percentage of English people living in the Midlands, but I have never personally heard this form used. It has to be "...to you," to be commonly understood.
Yes, "I can't sell you it," is correct but less common than the form used in this exercise.
Most likely one would say, "I can't sell you that."
"I can't sell it you," is used in England. Refer to this linguistic commentary on "Give it me." http://linguistics-research-digest.blogspot.ca/2014/01/give-it-me_27.html
@TahitiTrotsky: I have indeed heard "Give it me" used in the Midlands, and also "Give it him". But I can't remember ever hearing this construction used with other verbs. Have you actually heard "I'll sell it you", or are you simply inferring it from the blog about "give"?
@daughterofAlbion. My family is from Lancashire, and I grew up in Canada. "I can't sell it you" sounded like how my relatives spoke and led me to look up the link I posted. So, the blog echoed my original opinion; for me, "sell" fits the "give" or "tell" examples of (AltDOC) mentioned in the blog. Here is a "send it me" link; http://eng.sagepub.com/content/44/2/138.abstract Here is an academic paper with lots of examples: http://www.isle-linguistics.org/resources/Biggs--passive_variation--2014.pdf
@TahitiTrotsky: thanks for the links; they are very interesting. It's intriguing though that the first link is arguing that the usage is dying, and "has gradually been restricted to...Northern British speakers", whilst the second paper treats it as a recent development.
I imagine it would be a word order thing (as it is in English), but I wonder how you would differentiate between the two sentiments in Russian (and which meaning this sentence intends):
I can't sell you that. [but I can sell you something else]
I can't sell that you you. [but I could sell it to someone else]
Of course there is the third option of I can't sell you that [but someone else might be able to sell it to you] - which, without formatting codes, we would have trouble expressing in written English but something tells me could be entirely possible in written Russian... maybe?
In Russian, that's less of a word-order thing than which words are stressed when spoken, like the italicized words in your example. However, without vocal emphasis/intonation, the Russian sentence structure puts the "news" at the end.
Не могу тебе это продать. I can't sell you that.
Не могу тебе продать это. I can't sell you that.
Не могу продать это тебе. I can't sell that to you.
Продать тебе это не могу. I can't sell you that.
Продавать is to sell something consistently, or without specifying a specific time, event, or even a sale. Продать is to sell a specific something at a specific time, in other words, a specific sale uses the verb продать.
Я хочу продавать машины. I want to sell cars (in the general sense, as a profession, not which specific cars).
Я хочу продать машины. I want to sell (some specific) cars (for example, my cars).
Depends on the context. If it is a hypothetical situation, we would say: «я не мог(ла) бы продать его/её вам/тебе». If it is just a past tense form of “can”, then it will be «я не мог(ла) продать его/её вам/тебе». Могла is the form used by girls or women. The choice between его and её depends on the gender of “it”. «Это» here would mean “this” rather than “it”. The choice between «вам» and «тебе» depends on what the buyer is to you. It is safer to use «вам» if it is an adult who is not part of your family and is much older than you, or any adult stranger who is not likely to become your friend.