Here are some thoughts.
Fountain pens can be broadly divided into two categories and this is true for everything we own.
1. Assets
2. Consumables
Naturally assets either hold their value and could even appreciate in value over time. Some examples include, our homes, land, gold, antiques and of course limited edition or rare fountain pens. I imagine that these could include vintage Pelikans, Parkers or limited edition pens.
Consumables are items that are used up overtime. Some examples would include cars, buildings, equipment and lower end fountain pens. Some that come to mine include Pelikano Juniors, Lamy Safaris.
Wearing an accounting hat, assets such as land, gold or investments can either be valued at cost or periodically revalued depending on the accounting rules that apply in your country. Meaning, some jurisdictions require assets to be valued at market value and some at historical cost. In general, such assets are not depreciated.
Consumables on the other hand such as cars, equipment diminish in value and are generally depreciated (allocate the cost) over time the estimated life of the item.
This means that some fountain pens belonging to the asset class need not be depreciated. Accordingly, the cost of the item is not factored in. Instead the focus will be on running cost i.e. cost of say repairs and ink.
For fountain pens which belong to consumables category, the cost of the pen would added into the cost of running as above.
So taking my Pelikano Junior as an example, the cost is SGD 7. If my Pelikan P110 is anything to go by, the Pelikano will easily have an estimated useful life of 20 years. BTW my Pelikan P110 still works fine and I estimate that it'll will be fine for at least another 10 years. Probably more. This works out to be SGD 0.35 a year. In terms of running cost, I take about 5 years to go through a bottle of Pelikan 4001 ink. The price is SGD 3.15 a bottle. So that works out to be SGD 0.63 a year. So with depreciation, I'm looking at SGD 0.98 a year.
For a high end pen like the Pelikan M800, the cost is SGD 350. This pen is well made and I estimate the pen to have a useful life of say 40 years. This works out to be SGD 8.75. So including running cost that's SGD 9.38 a year.
In my opinion, this already compares (without factoring depreciation of the pen) favourably with
1. Lamy multipen refill estimated to be SGD 10 (4 a year)
2. Lamy roller ball SGD 24 (4 a year probably more)
3. Lamy ballpoint SGD 8 (2 a year)
For a Pelikan Toledo, I've seen a used M700 selling for more than what I paid over 16 years for the pen. So clearly there's been appreciation for the those models that are no longer commonly available. In this example, the running cost will be just SGD 0.63 a year.
To top it off, here's where accounting fails, since it only focuses on mainly on historical costs (when clearly one needs to consider time value of money or opportunity cost but that's a whole new ball game). One needs to factor in the following:
1. Writing experience i.e. pen width, tactile feel, weight, grip etc
2. The appearance of the pen (it's very important for my wife especially the colour)
To compare a fountain pen with say a disposable biro is unfair. It would be like saying driving a Toyota Corolla is the same as a BMW. Don't get me wrong, I'm a big fan of Toyotas but the experience is completely different. If this were not the case, we would all be driving Toyotas or riding scooters given the high oil prices
Just my 2 cents.