Must haves for a corn snake?

Hi everyone! I usually stick to the python section of these forums but I have a friend who has recently caught the snake bug and is interested in getting his first snake! He is interested in getting a corn snake and has asked me to tell him exactly what he will have to plan on getting. I have read various care sheets, as has he, and some of them have some conflicting recommendations so I wanted to double check with the experts here for some clarification.

The biggest question I think is just whether they need a heat lamp, heat mat, or both? I have seen some people claim they use a heat mat only, but is there a risk of the ambient temperature not getting high enough if one goes that route?
The snake will be housed, at least initially, in a 30 gallon glass tank with a screen lid. I am reading that humidity is not a concern for them unless they encounter problems shedding, so that is good to hear.

Basically I am trying to provide him the most cost effective set up while still providing a healthy and ideal environment for the snake. So if we already have a tank, screen lid, locks and two matching hides, what else would you say is absolutely mandatory to have in place before bringing the snake home?

Thanks everyone, he is really excited to be getting into the hobby and I want him to have only good experiences! :)

No and yes, depending on where you live. Corn snakes are actually a north american snake so they are usually used to the ambient temperature in your home, unless you have air conditioning that keeps the cooler then 72F. In my case, my corn snake only gets a heat mat because it can reach 80F in my house during the summer. During the winter (with the furnace) It usually stays between 68-70F. But corn snakes naturally will get cold temperatures during the winter. As for humidity, it is still important but again, being a north american snake it will tolerate the humidity it naturally gets from the weather you experience. Heat mats only provide a hot spot (basking) if your corn snake requires a little more heat. I have never used a heat lamp for my corn snake. She is super healthy, a super eater, sheds great, and is growing like a weed.

Make sure you are monitoring your cage's temps and humidity before bringing the snake home. Humidity isn't a huge concern but you don't want the conditions desert like either. They are from Florida so the occasional misting, especially while shedding is particularly well received. It's a colubrid so they are a bit more active than a ball python so I like to put in a branch or plastic plant in the tank so they have more to move around on. Its not necessary however. I provide light for my snakes although they aren't basking lamps and also isn't necessary.

Get a heat pad and put it on a thermostat, even if it never gets turned on because conditions remain perfect its still not a bad idea to have it in case something dumb happens (IE you leave the window open in late fall and then it drops your room temp below 45 or so)

Thanks you guys! So heat mat only and no lamp. Is it correct that ideal temps are a hot spot of 85 and ambient temps of 75-80? Also do corn snakes hibernate during the winter? Is it possible to avoid this if so, and how does one go about preventing it?

No snake in the entire world hibernates, they brumate... which is just a way of saying slow down. It does happen when temperatures drop for a longer period of time. This happens during winter usually. If temperatures are kept up in the winter, then no, they will not brumate.

Awesome, I had a bad experience once with a green snake that seemed to go into brumation (thank you for the correction there) and never "woke up". Someone at the time had told me that it was likely due to either not eating enough before slowing down and starving, or eating too recently and the food rotting. I was only about 15 at the time so it was probably bad info and I had no internet resources available to me at the time so I am sure my husbandry was not spot on. :( I have been scared of it ever since.