So how and where do you get these now that the rank system is gone?

Is it setup like this:
Player grinds a bg until he hit 50k honor, then he can buy the epics?
or is it
Player grind a bg until he hits 50k honor, then he can buy the right to purchase the epics at an additional honor/mark cost?

Also where is the vendor?

r13 vs r10 sets..

R13:

Armor 1424
Stamina 164
Agility 143
Melee critical strike rating 56
Melee hit rating 50
Ranged critical strike rating 56
Ranged hit rating 50

R10:

Armor 1228
Stamina 120
Melee attack power 174
Melee critical strike rating 70
Melee hit rating 40
Ranged attack power 174
Ranged critical strike rating 70
Ranged hit rating 40

So by choosing r13 over r10 you gain:

Armor: +196
Stamina: +44
Agility: +143
Melee Attackpower: -174
Melee Critical Strike Rating: -14
Melee Hit Rating: +10

.. So, is it worth to pay the extra honor ?

Current prices (total) for the complete set:
65025 honor
70 AB marks
50 AV marks
30 WSG marks

Possibly a glitch but i doubt it, on the 3.3.5 PTR the legacy armor vendor is gone in the Hall of Legends. Replaced with the 70 PvP sets. Legacy weapons vendor is still there.

As a note, you cannot use this set for Transmogrification.