Wont cover what, everything to keep one or what. Im sure that 80$ should be enough to replace and restock things that I need to. Remember im not buying the Tank, Decor, Substrate,ect... Im only responsible to replenish food
Have your parents buy the wood to build you a custom enclosure for it; it will be cheaper than an aquarium. Aquarium-type setups invariably lead to stressed & unhealthy monitors that never get a chance to live as long as they should; you'll also find that the monitor will not be as calm as it could be in an aquarium-type setup.
$80 will definitely be enough to cover your food bill and the occasional replacement of light bulbs & such.
Happy birthday by the way!