Don't rush into this. Cost will vary with condition, but all will be costly.
Since you are now an RROC member, peruse the Flying Lady ads and post your needs in the RROC 'wanted' forum. Also peruse the forum to see what other members have said about anybody that you intend to deal with.
Remember that your SC grill is something that you can sell AFTER you are satisfied with a replacement S1 grill.