Like guitars and cars, buy a rifle that speaks to your heart and what YOU enjoy. If you buy for that reason, you really won't care if it goes up or down in price. If you buy a longrifle for investment, you're setting yourself up for disappointment.
Also, keep in mind that what brings a price is an item that means something to the person with money AT THAT POINT IN TIME. In other words, the item that someone wanted when they were a kid, that now they can afford. Young kids don't have the money, and old folks are usually looking to pass on to the next generation.
In 20 years will some rich guy want your longrifle? Only if we take kids shooting now and get them interested. Think on it.
Best wishes, and God Bless, Marc