How much are 1 dollar silver certificates worth?

Answer 1

It depends on their dates. For bills dated 1935 or 1957, unless they are crisp uncirculated, or have a relatively rare Series and signature combination, they are worth saving only as curiosities or using as spending money, especially the Series 1957, 1957A and 1957B issues (printed 1957-61, 1961-62 and 1962-63 respectively).

The various Series 1935 issues (which were printed between 1935 and 1963) are perhaps a bit more collectible; but in any case unless the bills are CU I wouldn't expect a lot from a coin dealer for them.
You need to provide the date of issue and an estimate of condition for an accurate estimate of the price.