Bit of a late reply;
The Romanian 2000 note is perhaps my favourite modern foreign (to me) note. I hope your booklet remembered to highlight that in the smaller solar system window (top left), there should be an even smaller square window inside it.
If you shine a narrow bright light (like a laser pointer) through that tiny square, it should create an image of the sun with radiant sun beam lines, and then have a dark spot, representing the moon covering a large amount of it.
IIRC, it was also the first polymer note in Europe.
Which reminds me, I really must buy a laser printer to try it out on my note. 😀
The UK halfpennies are nothing special. Think I've got something daft like 500 of those smaller half pennies myself. 😛
But still, sometimes the knowledge is more interesting & valuable than the coin itself.
Don't have anything to say about the other issues. I'm sure they're fun, just it's not my area really.