Oscar,
Welcome to the forum. A picture of the front and the case with any accessories would help.
That machine is a post WW II Class 15 clone. They were imported by the millions and although not overly collectable are very good machines. Technically it is not an antique either. To be an antique it has to be 100 years old or older.
If the machine is complete, in excellent working order, and has a good case I've seen them run anywhere from 30 to 65.00. The colored ones seem to go for more. Add in a complete set of attachments and the price sometimes goes up. It's fickle really.
If complete but in the normal condition with a broken case and no attachments perhaps $25.00. It all depends what someone is willing to pay for it.
Your location will also have a bearing on the price. Some areas they sell for more, some for less.
Joe