What is the typical cost to have a ball python for pet?

How much does it cost to maintain a ball python?

All the cost for food, equipments, etc. combined.

I'm not sure on the costs of the tank and such, because I used an old fishtank/aquarium that I had lying around.
I use heavy brown paper (the kind that comes in big rolls) for an easy-to-clean and cheap surface. Buy a couple heat pads, a full-spectrum aquarium bulb for reptiles (maybe around 20-30) and you should be set. Find some rocks outside, clean them off and you're good.
Get a structure for the snake to hide/coil in, and a water dish.
As for food, if you can train it to eat frozen/thawed rodents, you can mail order them online for a bulk discount. I'm not sure what the price is per batch; I haven't bought any in a year since she doesn't eat very often.
Also, it is recommended you get another enclosure for feeding, so the snake won't associate the tank being opened up as feed time, in case you just need to hold it or clean the tank.

I'll try to find my rat cost, but it's not that bad once you buy all the equipment.

What are those heat pads for? I know those heat pads used for transport tropical fish only last for 48~72 hours.

So most of the cost is the initial investment. Afterward, what else is needed besides food?

Let me say that in 25 years I have never had a ball python. Not my cup of tea I guess. But the principe is pretty much the same.

The heat pads are called under tank heaters, (UTH's). They electrical devices to stick to the bottom of an aquarium. They heat up. I personally don't like them, but they can be very good in certain situations. I am not sure what you use with fish, but I would assume they similar to the disposable heat packs we use to ship reptiles and keep the insulated box warm.

After the initial investment, the main costs will be, food, (a mouse or rat a week, after it reaches adult size every two to three weeks is fine.) Substrate change. And heating replacement, depending on the heating you are using. This won't happen constantly, but bulbs burn out, the UTH's die eventually. You may need to occasionally change out furnishings, branches, hides, water bowls, etc...

If you buy a baby ball, and put it in a 20 gal tank, (smaller is fine for a neonate, maybe even better,) at some point you are going to have to upgrade the whole set up. If money is a concern, as it normally is, you can set the baby up in a tub, (or as some of our British and down under friends would know it, a "click-clack"). A UTH can work great here if attached to a thermostat or rheostat. This is less expensive for the short term, then spend the money on an adult set up.

Yeah, I was referring to those disposable heat packs. They only last long enough for the shipping of pets. So I guess your heat pack is something new to me.

If I were to get a ball python or any kind of larger species of reptiles, I would try to get an enclosure big enough for their adult size. I don't know if it work exactly the same. When we stock fish, it is known that we should get a setup according to their full adult size rather than their current size. It is also in fact cheaper to get just one setup for the long run instead of having to upgrade later and end up with two setup.

It's not a bad idea, you just have to set it up properly, and it can take longer for the animal to adjust to the cage and become comfortable. I Keep most of my younglings in tubs, in a heated rack. 32 litre or 64 litre "Really Useful Boxes" are the ones I use mostly. They have almost 12" of height which I think is better, and for plastic tubs, are very secure. Most of the larger rubbermaid/sterilite type containers need some type of reenforcement to make sure they can't get out through the lid.

Fishbone, you also own cats. How is the cost of keeping a ball python compare to a cat?

1 snake to 1 cat????? I almost couldn't imagine

Overall, IF you get the snake set up correctly and the habitat right, There will be a bigger initial investment in the Ball python. I have had cats my whole life, and I think you generally don't need to spend a whole lot of money on, well, "stuff". You can if you want, but that is more for the human really. A cat can be made very happy as long as you love, play with, & take care of it. The old joke, "My cats favorite toy is an old piece of string." There isn't allot of need to buy new things, feeding dishes, litter pan, maybe a scratching post if you don't have something around already for the cat to use. (For example, I have an old wooden stool, I keep it just for the cats. I catnip it, and they are used to it, and that is their scratching post.) With a snake there will be greater initial cost.

But, as for regular maintenance, if both are taken care of properly, the cat will be more expensive. Food daily, litter regularly, that is more there in and of itself. If you live in an area where you need flea meds, add that. Any vaccinations. Vet visits. Random stuff like catnip. That list could go on, and that is just the basics.

Snake, a rodent a week, every two weeks for an adult. You can spend stupid money on substrates at a pet shop, but I find that to be foolish, and even then, if you spot clean, you still only need to completely change it every month at most, and that is erring on the side of caution, (which isn't necessarily a bad idea.) There is allot of other stuff people will try to sell you at pet shops, but most of it is frivilous junk.

All of this is ASSUMING YOU HAVE THE ENVIRONMENT SET UP PROPERLY. If it is too cold &/or too wet for extended periods, you will almost definitely have respiratory infections. If you don't clean the cage, you have a much higher risk of internal parasites. If you feed live, you have a higher risk of parasites, and if you feed live by just dumping it in and leaving it, you run the risk of it getting bitten. But all of that is controllable.