It is no longer possible to purchase a new TI85, but you are obviously free to do so over EBay or something. Just make sure its previous owner surrenders all dumped ROM files to you, or one of you will be breaking the law. You may have to physically destroy his computer and all removable media in the process, but it is definitely worth the trouble legally.

Seriously though, unless TI specifically tells that it does not want TI85 ROM there, it should not be much of a problem. Please note that TI itself distributes its latest ROMs as part of the TI83+ SDK, no calculator required.