I think it's almost the same, but not quite. There is the additional trouble of listing and shipping the item you have and then going to get a replacement item (if it's something you need replaced) that you have to take into account, so that makes up at least some difference.
You also run into a harder to quantify but still real question of whether you are happy enough with whatever it is that you don't want to bother. If I'm going to buy a stereo I would do research to find out which ones are the best fit for me, which ones are the best value, and where I can get them for cheap. If I dumpster dive and find one for free that is Good Enough (tm), then I'll likely just use that and not spend any more time thinking about it. It may not be the most optimal solution; I might be able to do a bunch of research sell, that one, and buy another for cheaper and have a net gain on the transaction, but if the difference is small enough it wouldn't really be worth the effort. I guess that goes back to the paragraph above. But on the other hand I might not have known that it would be a net gain until after the research, and the Good Enough (tm) standard would probably have made me disinclined to do the research in the first place.
So while your friend is not necessarily making the most rational decision, it is not necessarily completely irrational either. A bird in the hand may really be worth two in the bush.