There was no 325is in 1998. There was a 323is and a 328is. According to Edmunds and Kelley Blue Book in my area, The 323 should be dealer priced from $12,300 to 13,500. The 328 should be priced from $14,500 to $15,600. That is with every option offered that year and in excellent to outstanding condition. These are just guidelines, but they should give you some idea of price.
1995 325I, window tint, K&N, debaffled airbox, BMW #104 wheels, Nighthawk low beams, smoked side markers, smoked corners, smoked taillights, M3 stlye heated mirrors, various interior bits, Bosal cat-back.