Ive always heard the older than better as far as strings go.. Not always with woodwinds/brass as new things and keys are added. I am a flute player as well as a violinist, and ive love to get a new flute as mine is probably around 20 years old.. I don't have 1-2 keys on my flute that would be standard on a B-foot that would make some fingerings easier and such.
I don't think anything that will be "produced cheaply" will be quality matched to the older beautiful European instruments.
I also wanted to add, string instruments value DOES go up. The more its played on the better the sound becomes. Unless it cracks or breaks or something, i don't think the value would go down, but I may be wrong.
I'm a violin player, and in my opinion, the older the violin, the better quality of sound produced. This is not the same for ALL violins, as sometimes the strings are a really bad quality, and just make the violin sound tinny and gross.
The most expensive violins are always (and most likely always will be) are brand new violins from specility string shops, the prices can reach up to about $10,000 (that's the most expensive that I have come across).
My advice would be to buy a second-hand violin, and if you think it sounds awful, buy GOOD QUALITY strings (these are more expensive, but produce better sound).
i think that is a generalisation that has arisen. some modern violin makers produce violins just as good as old, it is the mass produced violins that have kind of given the modern violin a bad name. i mean in some places it takes a person about ten minutes to make a back for a violin. so naturally you would think that these would not have the greater craftsmanship which would then lead to greater sound. there is too the fact that violins can mellow and grow into their sound as they age. i would gladly buy a good quality hand made violin