It's a great part of the hobby which, with a few exceptions, will not break the bank.
I don't believe anyone actually knows how many stamps it would take to have a complete collection of every town on every stamp which used every type of precancel device.
I've heard estimates of anywhere from 500,000 to over 1.5 million stamps. So, you can pursue this forever and are not likely to run out of stamps to find!
