As a business person, I say "no no no" to partners in any undertaking. Even among rich, experienced business folks, most partnerships end in lawsuits.
I mentor entrepreneurs, and I've observed something. People think they need a "partner" when starting a business or some other undertaking for one reason: Fear. They may lack the self-confidence to do it by themselves. Or they're worried about the financial or time commitment involved and they think a partner will spread the $$ risk, lessen the work, and double the chance of success. When in fact the opposite of all that is true.
So first thought is, your desire for a partner really means you're not sure buying this machine is such a great idea, so you want to spread the "risk" around.
If you're sure buying this machine is such a great idea, find a way to do it on your own.