The budget travel guide to national parks that applies globally, because park entry systems have common patterns worth knowing.

The free access days/periods: many national parks globally have designated free entry periods. US National Parks have free days (Veterans Day, Martin Luther King Day, several others). South African national parks have wildly varying rates by nationality. Research the specific park's free access policy before assuming you need to pay full price.

The annual pass calculations: for any country where you're planning 3+ national park visits, research the annual pass. The US America the Beautiful pass ($80) covers unlimited entry to all National Parks, National Forests, and Bureau of Land Management sites for one year — it pays for itself in 4-5 park visits. New Zealand's DOC campsites can be covered by a similar annual pass.

The side entrance approach: many major national parks have multiple entry points. The main entrance has peak queuing and often peak pricing for guided services. Side entrances (requiring research and sometimes navigation) often provide the same access with less competition.

The camping within vs outside calculation: camping inside national parks in the US averages $20-30/night (reserveable, book 6 months ahead in peak season). Camping just outside the park boundary on National Forest land costs $0-5 under dispersed camping rules. The landscape difference is often minimal.

The guide vs self-guided calculation: in some parks (Kruger, Galápagos), guided access is mandatory or dramatically superior for wildlife sightings. In most hiking-oriented parks, self-guided access with good trail maps costs nothing and provides the same experience as a guide at 10x the cost.