I noticed too that fusion stones for gold are more expensive here. I'm not sure about the under 3k stone, but the around 5,7k i used to buy with 1 sta and 0-2 random stats are aprox 11,2k here. The NPC that sells them is the same, except it's in lost island of atlantis now.
Arcane transmutor has a build in random fusion stone feature, the second option out of the 3 available (first is regular arcane transmutor, 3rd is the ones which stores and uses purified fusion stones), and this random fusion stone option uses up 10k gold instead of a fusion stone. So you just click on the 2nd option, place the item you want to use, and it will cost you 10k gold instead of placing a fusion stone.
About how high the tier for trash items - i dont know, i'm not an end game player yet, but i asked in my guild and nobody knew if there was a place to farm trash T7 or T8 items for tiering. It was one of those awkward silence moments, followed by "we dont know" 
. As far as i've seen on AH T7 or T8 are dungeon (or possibly crafted) items. Phirius shells gear is T6.