30 gallon is deffinately a little big for a little guy like that. I would stray away from an aquarium. Heres what you do!!

Go to Walmart, buy a 15qt sterilite tub.*Don't forget the top!!

Polk holes in the tub/ 1/4in holes should be good not too many, you want to be able to hold humidity.

Buy some aspen, zoomed heat pad(not moms heating pad), and look for a reptile rheostat dimmer to control your heatpad. Heating pads get to hot for ball pythons, and need to be regulated in order to properly hold the right temperature for their basking spot.*DO NOT RISK NOT GETTING A RHEOSTAT, IT CAN RESULT IN LIFE THREATENING BURNS!!

Buy or make some kind of hide, there are nice stickies in here on good choices. Something smaller would be better, they like tight spaces.

Water Dish

After that your golden. Tubs are the way to go. Not that aesthetically pleasing, but more functional then a tank. A tank for a Ball Python in IMO is an investment. The vented top doesn't allow it to properly hold humidity during shedding, and really make the snake feel unsecure. The open sides make it seem like they are out in the open. If your going to use a tank, use a ten gallon, buy plexi glass to cover 50% of the tank, cover all sides with black background, and buy clips to keep it from escaping. Make sure you monitor it during shedding because again humidity can be a problem with aquariums. Good Luck, hoped this helped!!