I don't even feel like the two senses in which it describes a product are different denotatively. They might be listed as two definitions provided in a dictionary but if you look at them they mean the same thing: inexpensive.
The thing is that while the adjective technically modifies one noun, what you're actually describing is something else that's closely related to it.
Look at these great shoes I bought. They were cheap too!
What you're actually describing is the price tag on the shoes. The shoes are the same regardless of the price tag.
I bought these last month and they're already falling apart! What cheap shoes!
Here, what you're describing is the manufacturing of the shoes. It was low-cost, inexpensive (in other words, cheap) manufacturing. The low quality of the shoes has allowed you to infer that the manufacturing was cheap.
If you call a person cheap, it's again the same denotative meaning, but again is applied to something else that's closely related to the person--the kinds of products they buy.
But there's also a different sense that is similar but not quite the same, when you're discussing effort rather than resources. Examples are as in cheap tactics or taking cheap shots.
Generally there's no expense monetarily but it's still similar in that what's being described produces results for little effort.