I ask that question all the time. Just picked this one up from Peru (2 images of different planes + Pilot):
It's a bit overpriced considering how recent it was released (2005). You might want to get a later revised version (like SteveinTampa posted) or the Netherland Antilles 2.5 Gulden (all around $5.00 for UNC). Another popular banknote which features both pilot & airplane on its design is this Lithuanian classic which also has several variations. The 2007 (P-68) is very affordable compared to the earlier versions (which I'm still seeking):
Just arrived today: Something about Swedish notes always makes them seem older than they actually are. Abkhazia is a de facto independent region recognized by almost everybody but Russia as territory of Georgia. Got to love the colors and imagery here. Always going to miss the diverse imagery of banknotes from before the Euro. Not much to say but this is what money should look like. Issued to celebrate the 40th anniversary of Djibouti's independence. Love the depiction of the whale shark here.
Some of my collecting is kind of random, but there is a "method to the madness" sometimes. Been trying to collect the last of the old Mexican peso notes (1905-1991); the last type for each denomination before they switched to the "new peso" in 1992. With these 3 I have all but the 4 highest denominations (10,000, 20,000, 50,000 and 100,000). Some of those are kind of pricey in decent condition but someday hope to have those too. Anyway, last of the old 5, 50, and 100 peso notes:
Mexico is a fun country to collect. Great, if have you travelled there & there are few tougher ones (sleepers, like you mentioned) that still remain accessible in higher grades. Here's a trio that are fairly cheap in UNC:
Indeed, have those; so far I have the last of the Mexican notes of each denomination pre-1992 from 1 peso up to 5000; 10,000 and above is what I'll try to work towards next. You could make an entire collection of nothing but Mexican banknotes, and I'm sure quite a few have. There's quite a diversity of them.
My favorite is the 20,000. I have one from circulation/travels, and an UNC example of the similar 20 nuevos pesos. I have either the 50,000 or 50 nuevos, but stopped there. Mexican notes are great to collect. So many of them with so many interesting designs.
When they switched to the new peso in 1992 (1000 pesos = 1 nuevo peso), they briefly kept a few of the high denomination note designs, but 10,000 became 10 new pesos, 20,000 became 20 new pesos, etc. Little while later they came up with entirely new designs and quit putting "new" in the peso anymore.
The dark cloud of hyperinflation: Imagine if we had to deal with that (000 lopped off our notes- a $1000 becoming the value of $1.00) & even the "new" version gets another whack (like in Zimbabwe or Venezuela).
Thankfully it didn't get that bad in Mexico, they managed to stabilize at some point before things got too crazy. I actually have a collection of all the periods of hyperinflation that resulted in banknotes denominated 1 billion or more. Zimbabwe got up to 100 trillion before they effectively suspended the currency for a "do-over." I'm pretty sure some enterprising Zimbabweans figured out they could sell the currency to collectors for more than they were nominally worth lol.
Yes- fortunately & one of the reasons some of the higher denominations go for a pretty penny today (these mid-80's series were expensive for Mexicans to tuck away prior to hyperinflation). Here's one (P-93a) Series A (first prefix) I picked up from auction. This is one of the notes that had "000" lopped off for "50 new pesos" (an example I'd like to get):
Old enough to be "classic" yet? Want to grab one of these before it got too expensive to get one (it's surprisingly difficult to find one of these in AU/UNC condition as not many thought these were worth saving, yet): Just always loved the scroll work on "United States of America" on the obverse. I already miss this design before all of out money went "big head" on us.