I guess you will need

- 5 millions of GIL
- at least one 3 star crafter
- at least one crafter 100% upped in Desynthesis
- to have beaten Coil2 Savage Mode
- a Level 15+ Choccobo
- to have dyed a complete AF set
- to have cleared the 3.000 FATE achievement

and then you can get a small personal house but Gardens are coming later. Much later.