No problem. El Salvador (& even Ecuador) aren't that expensive
for the time being.
If there's one thing I cannot stress enough- & that is, currency collectors from the US nickname world coins/currency "
Dark" for a reason. The majority of the nations
fly under their radar. A small percentage may buy older UK, AUD, CDN, CFK (some Caribbean, African, Panama & colonies) but for the most part, they're really not that interested in most other nations or modern World currency in general. If you don't believe this, just check out any banknote from the Philippines with any USA reference (presidential portraits or US slogans such as "Victory" on the back) & you will discover that these notes are 10-25X the SCWPM BV because they're so popular. All other series are still dollars & cents. US collectors typically drive the World market (though this is beginning to change*). They currently drive the market on Canadian banknotes (there are more US collectors who collect CDN currency than Canadian collectors).
So Panama will always be very expensive b/c of the strong ties to the US (the US helped the region gain its "independence" from Columbia in the late 19th century & the 2 countries remain very connected due to their reliance on the US built canal). The majority of collectors (from the US) know this was a super short series.
So El Salvador, which now uses the USD is still relatively cheap (like Ecuador), despite the fact that both countries stopped issuing their own currency decades ago. You can buy an
UNC 1 Colon for $10 USD on eBay. (Most notes you'll buy from these 2 countries come from US dealers). I bought the same note (from the same seller) for about $8.00 2 years ago so the prices are slowly going up.
*Successful middle class emigrants out of China & India (Bangladesh, etc) have moved to US, Canada, UK, Australia & other countries & have heated up their markets for their nation's currency. I've seen the same phenomenon with banknotes from Israel & other countries (forget the SCWPM BV's).