By that point EVERY slot has a grand company item. I had one in all my non accessory slots and a ring.This one sells many gatherer items from 5 to 11.
http://ffxiv.gamerescape.com/wiki/Me...lver_Bazaar%29
This one sells many gatherer items from 9 to 15.
http://ffxiv.gamerescape.com/wiki/In..._%28Horizon%29
This one sells many gatherer items from 15 to 20.
http://ffxiv.gamerescape.com/wiki/Me...lden_Bazaar%29
This one sells many gatherer items from 18 to 25.
http://ffxiv.gamerescape.com/wiki/In...8Vesper_Bay%29
This one sells many gatherer items from 25 to 30.
http://ffxiv.gamerescape.com/wiki/Rianne
This one sells many gatherer items from 27 to 35.
http://ffxiv.gamerescape.com/wiki/Me...sta_del_Sol%29
This one sells many gatherer items from 32 to 38.
http://ffxiv.gamerescape.com/wiki/Me...l_Phenomena%29
This one sells many gatherer items from 40 to 42. I couldn't find anything between this and the previous one.
http://ffxiv.gamerescape.com/wiki/Me...ebrim_Front%29
This one sells many gatherer items from 43 to 46.
http://ffxiv.gamerescape.com/wiki/Me...amp_Bluefog%29
And that's it. I couldn't find a vendor to fill the gap between 46 and 50. Keep in mind that there are many more vendors for the levels I said than I listed here.