Can i get a mytouch 4g?

I recently broke my mytouch 3g and they said they were not going to replace it, which bummed me out. Sooo...my friend said i can buy a mytouch 4g or 3g on amazon and all i have to do is move my sd card and sim card. I currently do not have a plan. Can i do that? I really dont want to waste money so i need an affirmative answer. thank you in advance!