purchasing a m03 or m05 help

[ch!3f]

hi guys im looking in to buying a m03 or m05 mini to race and basicly im running on a tight budget and it would be in the next month or so when i would be looking to buy 1.

to be honest i dont mind second hand but i would prefer new hence why im asking the questions.

i have seen that they do a m03r which looks the business but is it still all plastic?

1st off is which is the stronger chassis parts wise such as c hubs steering knuckles so on?
2nd which is cheaper for parts?
3rd would i be better off just to buy second hand if the price is right alsowhat kind of price would i be looking at for a roller second hand?

any help would be appreciated thanks in advance ian