buy things as cheaply/cheap as possible

[Evaviva]

As far as I know, "cheap" can be used as an adverb, eg "buy / sell / get sth cheap " (quoted from Oxford Advanced Learner's Dictionary)
So I don't know which one to choose in the following sentence:
He buys fruit and vegetables as _____ as he can. then he sells them to his customers at a little higher prices.
A cheap B cheaply
Please shed some light on me

 

[probus]

Both cheap and cheaply are correct.

"At slightly higher prices" is more natural than "at a little higher prices." "A little higher price" works well in the singular, but not so well in the plural.

 

[MikeNewYork]

Some words in English have two adverbial forms. Sometimes they can be used interchangeably, but at other times they cannot.
This also occurs with right/rightly and wrong/wrongly, as two examples. In many case, the -ly version is preferred in direct apposition to an adjective or verb, as in "the case was wrongly decided".

In your case, I would use "cheaply", but "cheap" would not be wrong.

The word "then" needs to be capitalized and the end would be better as "a slightly higher price".

 

[Evaviva]

In your case, I would use "cheaply", but "cheap" would not be wrong.

Well, could you please tell me why you would use cheaply? There must be some subtle applications.

 

[MikeNewYork]

Yes, subtle. For me "buy cheaply" refers more to the action and "buy cheap" refers more to the result.