@Woodchipper
Hey John. Fountain pens are fascinating, it is why they have become my passion. While in ballpoints and rollerballs, the purchased refill is 2/3 of the writing experience. That's because it includes the ink and the means to apply it to the paper. The feel and look of the pen is the other 1/3.
With fountain pens however it is more complex. This is one of the reasons that they are becoming so much more popular in recent years. The diversity of all the components, makes the fountain pen a very personal experience.
At one time in history, Ink for fountain pens was very basic in colour choice. Today, the choices of ink colour are almost limitless. They come in every colour in the rainbow and can also shimmer or contain gold flecks. The chemical make-up of ink just as diverse.
The reservoir is also quite diverse, with Cartridge/Converter (CC) being the most common today. As mentioned above, International Standard Cartridges abound, their are also a quite a few proprietary designs. Converters are even more diverse, because not only are some proprietary in shape, but there are a variety of designs that are Standard International comparable. On top of the converters, there are a number of different built in reservoirs, that employ silicone sacs, levers, pistons etc...
The next step is the nib and feed. This is the method of actually applying ink to paper. Any nib will write but how it feels, when writing, is a very personal thing. Nibs and feeds are generally kept together and are not interchangeable between manufacturers. That said, there are only a few manufacturers that supply the vast majority of distributors, suppliers, kit makers and pen makers. Many of the big name pen makers such as Pilot, Montblanc etc... make their own nibs in house and there is now a few Artisan makers that produce their own nibs. The tip of the nib is the business end, and it not only comes in many sizes and shapes, it is adjustable, with the proper techniques. There are nibs as sharp pointed as a hypodermic needle to as broad as 2mm or more. Even the shape of the point is varied.
As
@More4dan mentioned above, many fountain pen users snub the kit pen, mainly because of the nib. Some because it is "cheap Chinese nock off" and others because they have had bad writing experiences with them. The first is often a huge misnomer, as many of the kit nibs come from one of the big manufacturers I mentioned above. However they are often a less expensive, lower tier (lower quality control), than brand names. This isn't necessarily bad, as almost any nib can be tuned to write well. However sometimes the lower quality cannot be overcome by tuning.
The last aspect of the journey, is the pen design itself. This is the portion we are most familiar with and is where Ballpoints, Rollerballs and Fountain Pens are all equally diverse.
This has been a long winded way of addressing your original question about the ink availability. The ink is only a small part of the fountain pen experience. Odds are that anyone who buys your fountain pen will know where to get ink, and in short order you will likely discover many local sources yourself. You mentioned that you are adding this because the museum sponsors are fountain pen lovers. If they are like the majority of FP Lovers I have met, they will be more that willing to aid you in learning your way around fountain pens. This includes pointing you to local ink sources as well as constructively critiquing your pen. They may be able to point you to a local club/group. If your really lucky, you may even find one who enjoys tuning and repairing nibs and is willing to give you some guidance.
A good learning resource is Brian Goulet's
Pen 101
Here is a link to a great article.
Pens are Back
Good luck with you museum showing.