How much your silvertone guitar is worth depends on many things such as its age, condition and how well it is playing. It is advisable to take it to technicians at a music equipment store who can examine it professionally and give it it's true worth.
3 Additional Answers
The Silvertone Guitars are not worth much. Most in great shape go for around $40 to $80. Silvertone Guitar packages that include the case, music, pick, etc can be worth around $100-$200 in new condition.
The best thing that you can do is to take it to a music store and let them look at it. The value will depend greatly on the condition. There are websites that can help, but they will most likely charge a fee.
Silvertone guitars vary in price depending on different factors including age of the guitar. Your best bet is to check your local paper and see if a private buyer is looking to buy a guitar. You could also go to your local guitar shop and they can probably tell you how much it's worth.