I know that it's been some time and that you might no longer be active here, or interested in hearing where the word derives from, I would like to just drop this entry into an etymological digital portal as I found it interesting myself: http://etymologiebank.ivdnt.org/trefwoord/goedkoop
so koperen is not copper?
"abkupfern" comes from the copperwork times, so they would copy some image/design (on/from wood?) into/onto copper
I'm not trying to say that it comes from copper, as it really rather tends to "kaufen" .. but those -whether coincidences or not-, might still have all along influenced speech somewhat, as ofc. people used to call their coins by what they were made of
One could regard inexpensive as a neutral word. Cheap has, perhaps, negative connotations, and bargain (as an adjective) is often seen as positive. Where does goedkoop sit on this scale? Can a person be "goedkoop" because he won't spend money? Does goedkoop imply "cheap and poor quality" or "a good quality inexpensive purchase, a bargain", or does it have no connotations other than "not expensive"?
Is a "goedkoop" meal one you would be content to buy for you wife or watchful mother-in-law? Or only for someone you would rather not be eating with again?