Hi Erix993:
Is your ashtray the dashboard mounted style or the center console style? I think the dashboard style is common from 73-87 and are readily available as new from a couple of parts suppliers in the $25 range. The console mounted ones are fancier with chrome plating and an integral flip up lid...these are more expensive and range from $50-75 and available from a couple of suppliers.
If you have the fancier one and the exterior chrome is OK, just refurbish the interior of it as others have suggested...CLR treat the assembly and then paint the interior black or something to keep it from rusting as long as you dont use it for cigarettes or cigars anymore....or maybe apply one of those cheapo phosphatizing kits to the interior.
Regards,
Henry