Some people think they are worth plenty. The truth is less filling… Want to know what your machine is worth? A great resource is the ISMACS (International Sewing Machine Collectors’ Society). Give it a read and click the link below:
http://ismacs.net/sewing_machine_articles/how_much_is_my_sewing_machine_worth.html
But wait! Why are people selling them online for so much? Well, if it is serviced or reconditioned, then much of the cost is included in the servicing. You should always ask what the servicing included. Taking into account the condition of the machine and the the cost of a typical sewing machine full servicing, and the higher cost looks more reasonable…
Professionally Restored Vintage Fine Quality Sewing Machines 