All a leopard gecko needs is a hide in the warm side, a moist hide (easy to make with a tupperware container) a dish for calium powder(if you dont dust the crickets they lick it up when they need it) a water dish, and some stuff for it to cimb on(Oryx loves to climb), the tank only needs to be 10-20gallons which isn't too big, my 20gallon only cost 50$ and then the heating supplies, my personal costing was:
Tank: 50$
Hide(for warm side):15$
Heat: UTH 20$ Lamp 20$ bulb 6$
Moist hide: 2$ Tupperware, 6$ for moss (you get two huge bricks that you add water to and they expand, itll literally last you years)
ReptiCarpet: 10$
Wood to climb on: 15$
Hammock: 10$
Small Dishes: 2$ each
so the cost estimate for the NECESSITIES (some of the things I listed are just me spoiling her) 84$ according to the prices of what I bought, plus the price of the gecko, but again prices in my area may be different than in yours. The hides can be made yourself very easily and if your parents have gardening supplies around you can use peatmoss in the moist hide instead of the special forest moss (I'm using peat moss now). They recommend some kind of dirt/moss instead of papertowel because they can dig to lay eggs if female, and it hold moisture better. I got a Tangerine Tornado Leopard Gecko from my local pet store for 50$, when they're sold online for 300$+ so just talk to the sales person for a bit because getting deals isn't always as hard as you think!