In many ways, finding some of the low values can be just as hard as finding the higher ones. This is compounded by the fact that the catalogue prices for certain low value stamps have not moved for many years, despite some of them being quite scarce in their own right. The reality is that pre-1940 stamps that value at 25c (from any country) can be hard to find online. The best solution is probably to look out for inexpensive collections from which to pillage the values you need. We occasionaly have collections of low value (and sometimes modern) Latin America for sale. If you are after something specific, please get in touch.