The main question of financing a pinball. Get an interest free credit card and plan to pay it off over 15-18 months...whatever it is. I don’t think you’ll find anyone willing to give you a loan for this.
The above advice is NOT a smart move. If you’re looking for investments...this (all your collectibles) is about as risky as you get. Assume you will loose all of your money you put in and only buy these things because you like it. Just don’t expect anyone to fund your obsession...that’s all on you. If you do make bank on it in the future...good for you, but I think you’re more likely to get struck by lightening.
As far as the smart ass remarks on this thread. I think most are dumbfounded at why anyone would do this. If you have money to burn/can afford it out of pocket, great. If not...well, that’s why we are dumbfounded.