How much plastic have fast food chains given away in the past 40+ years? I've no idea, but it's a lot, and the environmental impact must be huge. Yeah, nowadays they claim to recycle old happy meal toys in to plastic play areas but that's hardly going to make up for it is it?
But the thing is, these things are collectable. And the older stuff is likely to be more collectable because not everyone kept these items.
Below is a set of 4 McDonalds pens with pen toppers from the early 1980s - Ronald McDonald, Mayor McCheese, Hamburlgar and Grimace. There was also an Officer pen, which I'm sure I had but can't locate.
Price-wise, I would've thought these pens in decent appearance would be £10+ each. After this period of time the pens are unlikely to work, so I don't think that would be a factor on price.