I went to petco today and say a Zilla Kit Snakes 20-Gallon Long and i was 139 and it comes with everything!
http://www.cheappetproducts.net/SNAKE_KIT_ZILLA_20LONG-P68839.html
Not sure why its not on petco.com
Sure, "everything"... But you won't use half of it.
The thermometer and humidity gauge are the cheap dial type, which tend to be as much as 20 degrees/percent off. Highly inaccurate, and so NOT worth the trouble. You need digital thermometers to monitor your snake's temps. And when it comes to corn snakes, humidity isn't enough of an issue to bother with any sort of gauge.
Heat lamps are NOT recommended for snakes. Even arboreal and/or high-temp snakes, for whom heat pads aren't totally sufficient, there are other, better options. Most definitely, 2 heat lamps that cover the whole cage would be a horrible idea as it doesn't give the snake any room to escape the heat. You should heat your snake's enclosure with an Under Tank Heater (aka heat pad/mat or UTH), under one end of the enclosure... approximately 1/3rd of the floor space.
The humidifying spray is a total waste of money; plain ol' water straight from the tap does just as well.
You need a minimum of two hides for your snake, so you would still have to buy one more hide.
The substrate that comes with this kit is OK, but not generally recommended for corn snakes.
So, all in all, you're paying an extra $70 for a bunch of junk you don't need. You'd be better off buying the tank alone (usually ~$70) and then buying your supplies (UTH, thermostat, bedding, etc) separately. This kit is not worth it, to say the least.
For what it's worth, here's a suggestion.
The Bean Farm is a good online store that sells some pretty good reptile products. In particular, I would like to refer you to these:
Ultratherm UTHs (
http://beanfarm.com/index.php?cPath=1204_1206) which are a high quality yet relatively inexpensive option for under tank heating. For a 20L, the 11x11 inch heat pad would be perfect.
More important than even the heating element itself is the thermostat (or rheostat, though they constantly have to be monitored and "tweaked") used to control it (
http://beanfarm.com/index.php?cPath=1238). A controlling device is absolutely NECESSARY to make sure your snake's heat pad does not overheat. The average UTH can easily exceed 100*F, no matter what the packaging claims, and, for a corn snake, you need to make sure it doesn't get hotter than 90*F tops--ideally, no warmer than about 85*F (or any cooler than about 80*F). The Alife sold here for just under $30 is a good choice if you're trying to do this on the "cheap," but, if at all possible, I highly recommend the Herpstat (I hear the Helix is good, too, though I haven't personally used it). The quality of thermostats is usually proportional to their price. The cheaper the thermostat, the cheaper the quality and more likely it will fail. The Herpstat and Helix are more than 3 times the cost of the Alife, but they are a MUCH better quality thermostat. This means your snake's heating element will be much better controlled and you will be able to sleep better at night knowing the thermostat isn't going to fail at any minute. Take this advice from someone who has used both cheap and expensive thermostats. I have regretted every purchase of a cheap thermostat, but have never once regretted the purchase of my trusty Herpstat II. Two of the half-dozen or so cheap thermostats I have had have failed within 1-2 years, but my Herpstat II is still going strong after 3 years.
Woah, that turned out a whole lot longer than I expected, lol! Sorry for the novel. I hope you find this post to be helpful. =)