During the last few years, vintage fountain pen collecting has undergone a huge increase in popularity. Vintage fountains can be both beautiful and functional at the same time and make far more of a statement about you than a 20c ball point. The really good news is that fountain pens don't take up much space (unlike, for example, vintage cars!) so it's possible to contain a substantial collection in a modest chest or display cabinet.
I'll start by defining the term vintage - I'll take it to mean any fountain pen manufactured before about 1965. Fountain pen production took a dive in the early 1960's due to competition from cheaper ball-point pens. Many established manufacturers did not survive this competition. More recent fountain pens I would consider to be part of the "renaissance" of the fountain pen which started as surviving manufactures switched much of their production to high price models and special or limited editions.
Most collectors start out very generally, collecting anything they can get their hands on. Later most will specialize on a particular brand or era. I made most of my early purchases at local antique shops but I soon exhausted that supply and had to look further afield. ebay is a good source of fountain pens. On the plus side it exposes you to a global market. On the minus side, you have to compete in a global market. That means you will be bidding against cashed-up and highly dedicated collectors for good examples. With care, vigilance and a little knowledge however, bargains can still be had.
The vintage pens you find on ebay basically fall into two categories - those sold "as is" which generally require at least a new sac (the rubber bladder that holds the ink) or an overhaul of the various and more complex ink filling systems; and those sold as fully restored which are generally ready to use. Many pens sold "as is" are easy to restore to writing condition, you could send the pen to an expert and pay $20-$30 or more, depending on what is required. To replace a sac on a lever fill pen is generally quite straightforward and within the capability of anyone with a practical turn of mind. It can be done with a minimum of tools at a cost of a few dollars. Repairs on other types of filling mechanism are more complicated.
A few tips on buying. You've found a pen on ebay and want to know what to check.
The nib should preferably be the original and made of 14ct gold (18ct is rare in vintage pens) it should be straight and undamaged and have preserved some of the ultra-hard iridium tip. Nibs which are only gold plated or made of steel will usually be in poor condition.
The clip, cap bands and lever (vintage pens may have any combination of these from all to none) should preferably have the original plating (usually gold but sometimes nickel or chrome) intact. Where the plating is worn down to the underlying base metal, this is called brassing.
The barrel and cap should preferably show no more than modest wear and should be straight - banana-shaped pens are seen on ebay. The Cap and Barrel should be free of cracks, chips and bulges and should not have faded or be of uneven colour (unless this was intended by the manufacturer). The cap threads should be in good condition so that the cap screws on and comes to a firm stop and doesn't wobble.
The manufacturers imprint if there is one should be clearly legible on the side of the barrel.
If the pen passes all of these tests, see if you can find out what similar pens have sold for on ebay by searching with the same key words and checking "completed listings" box in the Seach Options panel at the left of the ebay window it. If you are bidding on ebay, all of the usual safe trading precautions and caveats apply. Make use of "ask seller a question" before you bid if you need more information. You will nearly always get a reply. If you live in a different country to the seller, don't forget to check that the seller is willing to ship the pen to your country and to ask the shipping cost.
What to collect? This is pretty much down to personal preference and depends to some extent on your geographical location. Popular brands from USA include Parker, Sheaffer, Waterman and Conklin. From the UK - Parker, Conway Stewart, Burnham, Swan and Onoto. From continental Europe - Pelikan, Mont Blanc, Aurora. Apologies to collectors whose favourite I haven't listed. There are hundreds of brands some of which have stood the test of time better than others.
More info. There are many web sites to consult for further information. For a reference book, it is hard to go past "Fountain Pens of the World" by Andreas Lambrou. It's a pretty expensive book and if your interest is specifically UK and USA, much of the information is in a less expensive book by the same author "Fountain Pens of the USA and UK"
I hope that this short introduction has been useful and interesting. If so, please use the voting button below. Check back in the next few weeks as I will be adding some illustrations.