Not to be repetitive, but prices from NPC vendors in any city vary with fame, so if you haven't figured this out yet, more fame = cheaper NPC goods. (Duh.)
Also, I'm not sure of this, but I think the higher your fame is, the more gil they'll give you when *you* sell items *to the NPC*. If anyone can confirm this that'd be awesome XD
Items most definitly sell for more gil for higher fame. On the main item I sell back, lvl 1 fame got me 497 gil, now (not sure of fame) I get 512 gil per.