Too late for this party ? Lol
A new tranny from tischer bmw is 3000 not including the clutch, lines, pressure plate, etc. It'll run you softly around the 4k to 4.5k on parts alone. Try finding a used one and go that route unless you're stacked on cash... so total you're looking around 6k ish to have it completed and working with all new parts. Worth it? To each their own but I would trade the car in and get one already made 6mt. I'm glad I got mine in stick before I made the horrible decision
Ill be getting a new tranny soon so pm me if you're still looking for more info on the cost