Getting married at 18

Good luck getting an Evo with a credit score of 0 and no co-signer to help you out on that. I really can't see that working.

Your better off keeping your eclipse and saving up money, then selling the eclipse and buying a Evo through a private seller which might be cheaper and actually better for you. But insurance is going to rape you, 18 driving an Evo with full coverage is going to be ~$500+ with a semi-clean record.

But its your decision and if you want it bad enough and have the money to pay for it then I say do it.