One of the main problems with stamp collecting is the tendency to paint oneself into a philatelic corner. Every collector soon gets to the point where the stamps that he needs to fill the empty spaces in his album become fewer and fewer. But the cost of each new acquisition becomes greater and greater. And for many collectors the pleasure of finding an inexpensive stamp is as great as getting a rarer variety so that the cost of their hobby keeps going up relative to the enjoyment that philately provides.
There are many solutions for this and most of them involve specializing to a greater degree so as to decrease the universe of material that you are looking for and the popularity of items that you need. County and town postal history is a specialty that fits this requirement very nicely. I chose my county, Montgomery, in Pennsylvania. In the nineteenth century there were hundreds of smaller towns in Montgomery County, and most of them had post offices. I always keep my eyes open for covers that were used from Montgomery County towns and, even after years of looking, can often add items to my collection. More importantly, there are few collectors for each county