This too used to be on Quora.com but got taken down because they didn’t like me linking to an external website. 😦
It is theoretically possible to make your own tarot deck: I myself have done so. However, get this: the cost of finding an online company and getting them to turn my designs into a finished deck was approximately $45 – but that didn’t include any value placed on all the hours I had spent painting the designs, scanning them and editing them with Photoshop, etc. (I suppose could have cheated and just used pre-existing designs which are floating around the internet as pirated copies, but it would still cost me money to print them out).
Bear in mind however, that, Amazon is currently selling copies of the Rider Waite Deck for less than $20, so you must be really poor if you can’t afford that!