I have found that the more requirements one adds, the harder it will be to fulfill. Dulcimers overall are much cheaper than say guitars, banjos, violins, and mandolins. But when buyers set a very low $200 budget and want a quality dulcimer that's easy to play and sounds great , is also short scale , and also available within a couple weeks or so ... well if you eliminate just ONE of those six requirements it will open up a broader range of options.
It's kind of like the old business saying- everyone wants something that's fast, cheap, and high quality... pick two out of three.
Keep in mind that a 25" scale 'used to be' considered short scale. Standard McSpaddens are typically 28 1/2" scale length. People used to custom order 25" or 26" scale dulcimer if they had short fingers or arthritis. So don't think you need to get a 'travel size' dulcimer that's even shorter than that. Dulcimers that are shorter than 25" VSL (scale) have their own problems- the action may feel stiffer when pressing down the strings, and/or you may have to put on heavier strings in order to tune up to standard D tuning.
A 23.5" scale McSpadden Ginger model is typically tuned up to G (3 steps higher than normal D)..though you can tune to D if you put on heavier strings... but that will feel stiffer to fret. And it's rare to find a used Ginger for sale for $200.
There are pros and cons to all these factors. There can be disappointments in buying used instruments off Ebay if a low price is priority.
If you want a new dulcimer that's good quality and reliable for around $200, I suggest either the Bill Berg or David Lynch student models. Don't worry so much about scale length- as long as it's shorter than 28" she'll likely be fine...most fretting is done on the melody string anyway and you really don't have to do fancy long reach chords.
Those irritated by grain of sand best avoid beach.
-Strumelia proverb c.1990