Used cone's probably won't help you.  Best off seeing if anyone is selling a used spring conversion or take a look at the vendors across the pond.  

Anybody selling slightly used front donuts  for less? I cant afford to buy the new one.  Currently on a budget,( sad face icon)

I honestly believe that the two front donuts i have are worn out,,,, i tried searching it , i want to purchase one set, i wrote donut on search, it says no product found.... Haaay!!

The rubber and the metal cone are meant to be two pieces and not fused, the wieght of the car should keep them together.  This site helped me a lot with photos.  My  rubber was completely shot.  I ended up replacing with new quality rubber and adjustible height cones on all 4 corners.  There are 100s of threads on this forum, i recommend reading them.  Also consider going to a coilover setup.

Crack open the Haynes manual Not threaded they just sit together. Jack up the car then line them up and lower the car. Unless you have some worn out parts this should work.

Sir Dimitris, maybe you can help me, if i remember it right you posted a photo of your mini parked on the road and we all noticed that the right side of your mini is lowered, you said the donut were squeezed and need replacement, how did you do it?  Ty

i lifted my mini today on a jack to check the balljoint, i noticed that the cone is kinda slanted, i tried to hold the cone and it is moving, i suspect it got dislodged from the donut, question is , is it easy to fuse it back to the donut? How?? Is there some kind of a thread in there?? Thanks...

no wonder i felt  too much vibration on that side of the wheel.