Value
There is actually little logic involved in determining the value. The "market" itself determines what something is worth, or what is the amount for which it can actually be sold at that time.
To get a sense of realistic amounts, a reference book like "The official Vintage Guitar Price Guide" is a must. This is published annually (format old-fashioned telephone book) and, in addition to indicative prices for the various brands and the associated numerous versions, also provides specific information per instrument. Although the title suggests otherwise, you can also find recent construction years in the overviews. The guide also provides information on amplifiers, effects, and various other stringed instruments. The currency is in US dollars and because its exchange rate has fluctuated in recent years, you should always convert it to the current exchange rate.
Gbase, a site where American music stores can offer their used instruments, is also a good start to get an idea of the (asking) prices.
Prices in America are generally a bit lower than in Europe, so assume that you will often lose a little more in the Euro countries.
In addition to the amount for the purchase, you will have to deal with shipping costs (or perhaps you will pick it up yourself). In the case of purchases outside the EU, there is also such a thing as customs costs and VAT.
Europe
The costs for buying and shipping within Europe quickly become clear. You agree an amount for this and that is what you ultimately pay. My experience for shipping within Europe is that it will be a few tens. Have the package insured upon shipment.
Outside of Europe
For example, if you have your purchase shipped from America, you will have to deal with both customs costs and VAT. These are not only calculated on the amount of the purchase, but also on the actual costs of shipping. So add them together and convert that into euros. Please note that the rate will be in favor of the Bank / Credit Card / PayPal. So don't be surprised if those few percent deviate from the current rate. Then you have to add the costs for customs clearance and the Dutch VAT (21%) and you know what you will approximately lose. Assume a total of approx. 23% extra based on the amount of the purchase plus the costs of shipping. Customs may request interim proof in the form of invoices or transfer data. Do not try to "cheat" but just give up on reality, this prevents problems and unnecessary delay. Let this be immediately clear to the seller.
See the attached image with a calculation that serves only as a random example.
You will notice that your purchase does not arrive at your home as soon as it has arrived in the Netherlands, especially if you have a tracking code during transport, you will not miss it. Customs often hold the package for several weeks before it is released. Depending on the carrier, you sometimes receive an interim form on which the specifications must be completed. It is also possible that "Aunt Pos" suddenly appears at the door and the extra costs have to be paid immediately in cash.
Never let the sender specify a higher value than the purchase price (for insurance, for example). This amount can possibly be used to transfer VAT. You are then unnecessarily expensive.
My experience is that in practice, shipping from the US will be somewhere between 100 and 200 dollars. Sometimes much higher amounts are initially proposed, but a cheaper form of transport (or somewhat less quickly) can make a big difference in mutual consultation. If you want to have the purchase as soon as possible, there is a hefty amount. And do not forget that VAT is also charged on this.
You can of course buy an instrument during a foreign trip and take it with you as luggage on the way back. Here too, you must declare the purchase upon arrival in the Netherlands (above a certain amount). A weather then applies the surcharge for customs and the reimbursement for VAT. I myself have no experience with this. In order to safely take musical instruments on an airplane, you will have to study the possibilities and possible costs in advance.
Index
The development of the value is difficult to measure. Which brand, model, version, year of construction, current condition, etc. are involved? It is also possible that a certain instrument suddenly becomes popular as soon as a famous musician is seen with it. To get a bit of an idea, you could use the graph below as a guide. Based on an established list containing the well-known models by Fender, Gibson and Martin from the period 1950-1970, the value development of that total collection was examined. Keep in mind that the amounts are stated in dollars and that it concerns the American market. When measuring over a longer period of time, you should also take inflation into account.
On the left is the total value in Dollar, but it is not so much about the numbers but about the course. For example, the graph shows that prices have risen rapidly since 2001. From 2008 (crisis?) The decline started and from 2013 it seemed to be able to rise again. But past results. . .
The index appears to remain at about the same level until 2020 compared to the few previous years. However, because the dollar has become more expensive for the euro countries during that period, there may still be an increase in euros.
