The Zimbabwe notes are a difference catalogue to many of the current notes available in the market. This is how I see it.
Those Zimbabwe 2008 100 trillion notes issued back in 2008/2009 notes, were almost worthless the moment it was released. And because of that, many dealers in the west can get them by the bundles at a very cheap price, and on sold them for a profit. Slowly, the popularity for owning a trillion dollars note getting momentum, and everyone talks about getting one, and as such, prices went up. Then few years ago, it was reported that counterfeiting notes were reported for the 100 trillion note and suddenly, that made the genuine ones even more expensive. The question to my argument is the holding cost. If you (dealer) have bought them next to nothing, and now collectors are willing to pay $100 each or more, most likely you will not let it go cheap, after all the holding cost is almost minimum to them. I managed to get a full set from P65 ($1) to P91 (100 trillion) for US$37 in early 2010. The seller even provided me with the replacement prefix for the 100 trillion note too. I later went on and bought the 4 sets of 4 notes (10 to 100 trillion) for us$5 per set. Again, I was provided with few replacement prefixes, and with one radar note too.
The other note that came to mind with low holding cost was the China $10 Olympics 2008 notes. Many people in China got the notes, especially for those mum and dad non collectors, but would not let it go for just a $100? The holding cost is only 10 yuan, which is less that US$2. If that was me, I would do the same too. I remembered when it was first released, it was selling for $99 on eBay, and many were sold, before the price just skyrocketed few days later. I waited for a while and later I found a local dealer here selling it for just over $200 in March 2011, and I went and bought one.
The Suriname guilden note is again a difference story. I remembered talking to someone in the country back in 2000, trying to get one (and the 10000 guilden too), but was unsuccessful. To the local, this is a high value note and it was a lot of money in that country then. The collector wanted me to pay first and at that time, I had trust issues and would not want to risk it. I have a collector friend managed to get these two high value notes but at a very expensive price. High value notes are always a difference story as the holding cost is high and re selling them may take some time. Not many collectors would go for high value notes either, just like those 500 euro. I only have one 500 euro (2002 T prefix Ireland) in my collection. and one is more than enough, after all, the note is not doing anything but just sitting in the album.
This is just my 2 cents!