List price and sale price are usually different.
"All it needs" should be mentioned in the appraisal.
"All it needs" is usally a point of disagreement between the buyer and the seller.
Do you have a 3rd party for mediation?
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As to the garage door, the value would be small and certainly not enough to discount the home from 139,000 to 75000. There is nothing that is minor when it comes to upgrades of kitchens and baths, as you are suppose to bring things up to code if they are not already.
If you feel that by fixing the garage door and the "minor" upgrades will improve your home value drastically then do them first.
My recommendation as a certified appraiser and real estate broker, put the home on the market and give your brother a first right of refusal or do as Toni suggest below as she is correct that the time, money and stress will not be worth it.
As for the specific question related to cost of a new garage door and "minor" upgrades to kitchen and bath, I think that a difference of only 12,500 is an absolute bargain when involving the two most expensive rooms of a house - kitchen and bath. If you can get these items done for much less, then you should do so because it will raise the value of your home. Otherwise, reducing the price by 12,500 for those repairs and upgrades is minimal. I've seen buyers offer much less due to just the stress of having to "deal with" repairs and/or upgrades. I've seen buyers who would rather spend upwards of $20,000 and more just to avoid painting one room. ...it's amazing how many people just won't lift a finger and would rather pay....So, if the appraiser has only reduced it by that much and has based the opinion on those repairs and upgrades, I think you should be grateful. You can either sell it to your brother and let him put in some sweat equity, or repair the property yourselves for a higher valuation. The bottom line here is this - there is a value for labor and the stress of repairs, and you should not discount or minimize the value of each.