First of all you need to find out the licensing requirements in your state. In SA you don't need a license to keep one animal off the list but you can't sell, breed or otherwise dispose of it without permission.
Reptiles can cost anywhere from $50 ( cheap dragon hatchling ) to many thousands ( Green tree pythons, albinos etc .)
Enclosures can be anything from a click-clack plastic container costing around $10-$20 up to a custom built enclosure from someone like Steins enclosures costing thousands.
Heating can be as simple as a heat cord with a ceramic tile, a heat mat/pad or globes/ ceramic emitters or reptile specific radiant heat panels. This can cost anywhere from $20-$250.
You may or may not decide to use a thermostat, cheap off eBay $30ish up to around $180 - $250 for a microclimate or habistat depending on model.
Then there is lighting and if you keep dragons the need for UV tubes.
When this is all sorted there is water bowls, hides, substrate and cage furniture to consider.
Also there are the associated costs of food and electricity to take into account, plus the yearly license fee.
What you need to do is find out what you can keep in your state, decide what you want to keep and it's husbandry requirements.
The first step in this hobby is research and plenty of it, don't be afraid to ask questions however stupid they seem, no one was born a reptile keeping expert.
Hope this helps .
