You don't necessarily need bulbs for a Leopard gecko, they do better with belly heat so you should use an under the tank heater. I do use a 60 watt ceramic heat emitter in the winter if it gets too cold, and just for my own viewing pleasure I use a moonlight bulb just so I can see what they're doing. They are nocturnal so they don't need light at night. There are some studies about creating a day-cycle using UVB, but many Leo's are kept with belly heat and no lights for years. You also need at least 2 hides, one humid and one dry. The humid one can be filled with vermiculite/perlite mixture or sphagnum moss, I prefer the moss. This is to help them aid in shedding.
I personally would save your money and not buy the kit, you will not end up using a good majority of it. The sand is no good, as you have stated, the thermometer is not the right kind and those are usually off by a significant margin. You would do better to buy either a temp gun or a digital thermometer with a probe. A regular 10 gallon tank with a lid will work just fine and be cheaper than the set since you will have to buy some additional things anyways.
I keep my geckos in tubs on a rack, but I've had my breeding pair in a 20 gallon tank for a few years now. I keep the ambient temperature on the warm side around 80 degrees, it reaches 90 degrees on the floor where the UTH is, and the cool side ambient temperature is 70 degrees. I have a moist/humid hide with sphagnum moss and a dry hide. They mostly spend their time in the dry hide unless they are shedding, then they will hang out in the humid hide. For my humid hide I use a 16 oz deli cup that I've cut a 2 inch diameter hole in the top so they can climb down inside. The dry hide is just a cave you can get at the pet store. I keep a water dish clean and full at all times and a cap full of calcium powder for them as well. I use paper towels as substrate where they tend to defecate (the have a poop corner) and just use slate tile for the rest.
Here is a good site that gives you a complete run down of Leopard gecko care, and they use pretty simple and affordable things. If you don't really want a realistic looking enclosure they have great tips.
http://www.vmsherp.com/LCKeepingLeopards.htm