Question: how much does it cost to fix the gear shift?
Answer: If the cause turns out to be a loose shifter linkage, you can tighten it yourself at no cost, or have the repair-shop do it for $50-75. If the condition is being caused by a damaged shifter cable, the repair-shop will charge you $125-$250 for replacement, or you can purchase and replace it yourself for around $35-$80.