- Condition: Instruments in excellent condition, with no significant damage or signs of wear, are typically more valuable than those with scratches, dings, or other imperfections.
- Age: Vintage guitars from the 1960s and 1970s are generally more sought after and valuable than newer models.
- Originality: A bass that has not undergone significant modifications or repairs may be more valuable than one that has been altered.
Based on these factors, the value of a Guild M-85 bass guitar can range from around $1,000 to over $3,000, with well-preserved examples from the 1960s and early 1970s commanding higher prices. However, it's always a good idea to have a professional appraisal done to determine the accurate value of a specific guitar.