Cresteds won't need a heat lamp unless your house gets FREEZING. They like fairly comfortable room temperatures. :) I saw cresties at a convention today for 20 dollars, and some high end ones for over 100! All depends on color, pattern, age, and what most breeders are looking for.
If you go to a convention you'll find the cheapest prices as well as NO shipping--and getting to meet your guy in person.
I know people who keep their crested geckos in a 20 gallon tank turned on it's side. Other people even keep them in a tall sterilite tub. The size just needs to be appropriate to the gecko. They like to climb, but don't need a ridiculous amount of space. Those front opening cages are great, because it's easy to get to them without reaching over, but they are insanely expensive in pet stores. Sometimes people resell them for cheap(the 80 dollar front opening one in petsmart was 20 dollars at this show!)
Starter habitat size can be fairly small, they start out itty bitty as babies. You can also just buy their regular adult habitat from the start if you want. I might start mine out in a small tub on it's side with some fun decor and hides. Tubs are good for holding in humidity, which is your primary concern.
In general an adult needs the space of a 20 gallon tall(picture two ten gallons stacked on top of one another), but as babies you can start them out in a tub or ten gallon tank or something like that. They seem to thrive between the temps of 68-78, meaning many homes need no additional heat, other than the gecko maybe being in a warmer area of the house. Don't let them get above 85!
Crested gecko diet is CHEAP..I saw a huge bag of it for about 12 dollars. For a single gecko, that can last forever. Repashy is the best stuff. Best thing is they never NEED crickets, unless you want to give them to them as a treat!
They are cuuuute geckos. Almost bought one today. So close.
I'm actually interested in their much larger cousin, the "Leachie" gecko. EXPENSIVE...we're looking at 300 minimum for one of these guys(but a reptile breeder owes us money and can probably work out a trade with someone!)
What can we say...We like big, lol!