The NPC retailer prices are too high for the items of gear they are selling full stop. The prices do not change in accordance with server populations, as far as I know or else the prices listed on NPC items on FFXIV YG would be forever in flux, and they're not.

In answer to your "How can new players afford gear?" question. They can't do it with NPC items. You have to do it by way of earning gil from leves (or crafting w/e), and gearing up through leve rewards, which are often quite good actually, even if the gear colours are a little off.

The other thing mentioned by Perrin is purchasing items from PCs. That is the best way to go as equivalent items ought to be substantially cheaper by comparison at a retainer than from an NPC retailer.

Also, as a small note, and someone will probably disagree with me, while leveling if you find a higher level item that is cheaper than a lower level item (it's happened to me often enough), go ahead and buy it and use it. Yes, it will be gimped because it's the wrong level, but if the alternative is nothing at all, I would choose the lesser of two evils. In addition, at some point that item will be the right level anyhow so you'll get good full use of it eventually.