8 3/4 489 cost

Been in contact with a seller of an 8 3/4 surgrip with 355, gear,489 case, says is a good one for 650 I am only willing to pay 500 we are apart in price tho.This is only the pig.He is 2 hours from me also so I have not seen it.Ok what is a fare price now a days. Also how does one know if it is any good without installing it.