Selling a vintage guitar:
If you want to sell a modern instrument, you will sell it at a discount, as the potential buyer can buy the same one new. If you sell a vintage guitar, your chances of selling it, and selling it at a good price, depend on a few factors:
The reputation of the luthier who built the guitar. Favinos command higher prices than Di Mauro or Anastasio, for example. Busatos sell for higher prices than Favinos.
The reputation of the model. A # 10 Favino sells for much more than a model #1A, for example.
The number of frets to the body. A 14 frets sells for more than a 12 frets.
The kind of sound hole. The most desirable is the oval sound hole, D Holes are in between the oval and the round sound hole, which is the least desirable.
Provenance. Unless an expertise is available by a recognized luthier or expert, buyers want labels, serial numbers or plates.
The condition of the guitar. Scratches, dings, or cracks.
Parts are original or not (tuners, tailpiece).
Playability. Unless the vintage guitar was fully renovated by an experienced luthier and its playability is equivalent to a new instrument, many players will not buy a vintage instrument.
Sound quality. This should be the biggest factor, with playability.
Players and collectors like to try and thoroughly examine themselves and ask a luthier’s opinion about an instrument they are buying. If potential buyers and sellers can meet in person, it is best. If you buy an instrument from Ebay for example, it can be fine also provided you may return the guitar after an examination period. Brokers rarely misrepresent an instrument, have their own deserved credibility, and allow an instrument to be returned.
It is safe to write a disclaimer when selling an instrument.
A vintage instrument, produced more than half a century ago, sometimes seventy or eighty years ago, and played thousands of hours often by many owners and in all conditions, will never look like a modern instrument produced 3 months ago, never played before you put your hands on it, out of its box and still smelling the terrible varnish they apply on this kind of guitar. A vintage instrument is not for everybody. As an instrument it sounds superb, with the vintage tone, something you have virtually zero chance of getting from a modern instrument. Also there might be cracks and dings, frets might not be new, etc. When I sell a vintage instrument, which had a total renovation, I say it in the listing. If not clearly stated, it has not. If it says, I write for example: new frets, planned neck, reset neck, etc. If you do not want to be disappointed and impose on me return costs as I always accept returns with full payment, you need to be aware of what a vintage instrument is and protect both of us from disappointment and trouble. Pictures are never retouched and they also give a good indication of the condition.
There is no money to be made by selling vintage guitars, except you are a broker with a solid business model, with the risk remaining with the seller, a solid 20% commission, and no concern if the instrument sell or not, fast or not. Your chances of finding a superb instrument at an exceptionally low price are slim. Trading 75 instruments so far this year, I was lucky twice. And the extra profit on these two deals was swallowed by a dozen unlucky deals.
One more advice: Do not sell a gypsy guitar to someone who never player gypsy music. They can try the very best Busato, for example, but they do not have the right hand attack to generate the right sound. They will be disappointed and will return the instrument, with all the cost and trouble for you. I learnt the hard way!