Just to chip in. I spent about USD950 on my current machine at the beginning of this year. The key specs are:

E3-1230v2
EVGA GTX660 factory overclock
Asus H77 motherboard
120GB solid state drive
32GB RAM (I needed the extra for work, unrelated to FFXIV)
550W power supply
about $50 was spent on a new tower case.

The GTX660 is capable of running most of the game at maximum setting for a enjoyable experience.

But when I'm in a very crowded area, for example by the market during peak hours, I can sense the chat input becoming sluggish. When I chat it isn't as responsive as when I'm in a deserted area. However I think this may be a problem with FFXIV UI itself. I'm also more sensitive to these things because I work with a lot of text and editing all day.

Coming back to this setup, I wish I had invested into GTX 670. That's about all, I guess.