Where to find lists of cheap Cubes?
If you are on a budget, you probably don't want to buy any cards - by definition, for a Cube you need the best cards of all times. The power 9 alone would run you into the thousands of dollars.

You do have 2 inexpensive options:

Cube works with any set of cards, just take the best cards you have. No money involved, only time to decide on the cards. You don't have to use any list, just use whatever you have. Advantage: You learn a lot about your the cards in your collection and you have to make a conscious effort grading their relative power, which can only benefit you as a player.

Second, if you don't mind using proxies, simply take a cube list you like and print proxies of everything you are missing. There are many resources where you can get card scans, or use the Gatherer text for the latest errata. This will take some time to prepare the printing run, and depending on your circumstances, could cost you a few dollars for paper and/or ink. Advantage: You get to play the best cards of all times for crazy powerful decks, should be loads of fun, you (probably) get to know many new cards.