DS1 has had corn snakes for the last 3 years, they definitely need dedication and knowledge to care for them properly, but they aren't particularly difficult as long as you understand what they need. The initial cost was more than we expected. The snake was £40, but the vivarium, heat mat, thermostat (absolutely essential, do not listen to anyone who tells you they aren't!), digital thermometer, hides, vines/branches, fake plants, substrate etc pushed it up to about £300.
Neither of ours have escaped, but during breeding season (spring into summer) they really do try, you can find them pushing against the door or vents most days! Both males, not sure if females do the same. Size wise, both are fully grown, one is 4 foot, and one is just under 5 foot.
DS has had 2 bites from one snake, different occasions but both at feeding time, both drew blood but he says it isn't painful as their teeth are so small, 'imagine being hit with the hook side of velcro' is how he describes it. Second snake has never bitten. They have a defrosted mouse every 10-14 days depending on the weight of the mouse. Fresh water every day. DS spot cleans whenever he sees poo, usually once or twice per feed, and deep cleans once a month.
I disagree with the poster who says they smell. Ours really don't, at all. I actually just went and had a sniff in the vivs to be sure, just a woody smell from the aspen substrate!