Maybe?
Get in contact with those companies.
I don't really think there is a matter of any government regulations in the way (not like you are buying uranium ore after all), it is just that you need to make a cheapo company just to have it on paper that you want to buy their engines.
I think they would look at you weirdly, but in todays world anyone can buy anything if it means companies will get money and you aren't breaking the law (although you can bend it a little).
For instance I think there are some regulations of buying some chemicals and shiping them in country without permission, but I still bought like a kilo of Thiourea from the dog eating short people to make a little bit of my liquid tinning solution.