Your entire plan relies on data mining prices from websites that sell actual cards. They are not giving you an API that will reduce their clients. You need someone to do it for you.
Also, wouldnt your business kind of work as an "investment" firm, thus, needing some form of regulation / license from the government? You will be dealing with people's money in and out.
Third point, at first I thought you would just get comission money, but you also said you need a formula to reduce your risks. What exactly are your risks if you are just offering the platform for people to invest and risk their money? In case you do have a risk, shouldn't you already have your formula ready and also have tested it in many different scenarios
The idea itself os good (and you know it, otherwise you would have written it before the edit in the OP, its good not to share good business ideas), but it needs more work.
I suggest you to, for now, return the money with some loss and work on your plan better. Data mining might not be that difficult, having a script go through a set of webpages and read a determined value on it (card name/number and current price) isnt something difficult.
Having it run on 20 thousand different cards and store that data is something else that you dont need to do at first. Try finding someone that can do it for a few cards, once you see that it works, that your formula works, etc, then you are ready to scale it to 20k cards. I dont know how volatile is the market of cards, but I imagine you dont need more than 1 reading per minute. You will have big infrastructure / server costs in the long term, so keep that in mind.
Btw, I needed an app to gather some data for my phd thesis and I did it myself, with absolute no previous skills. I am sure a computer guy would code much more elegantly and would have a faster code, but for me my way was cheaper (myself doing it) and it was enough for me (Im actually impressed that I made my code run in less than 2 seconds running of a Raspberry Pi in my living room). You said you dont like it, but you might yet again try just to get this done by yourself, there are probably tutorials around on how to do it (gather specific data from webpages). As you said, you dont know much (or anything) about programming, but it is important that you at least understand the logic behind it so you can take the right decisions. Im not saying that you have to do the entire website, just the initial data gathering till you work your plan out.