How to get symbionts?

[Beni-Kujaku]

I know symbionts from Magic of Eberron have listed prices‚ and can be obtained through the Daelkyr halfblood class‚ but what about Fiend Folio ones? Are there rules to gain one of them beyond DM fiat?

[ShurikVch]

Ghostly Visage is available as a Familiar for Dread Necromancer
The rest of fiendish symbionts are Outsiders - thus, legal for Lesser Planar Binding

[Gruftzwerg]

Graft Flesh (feat)

found in the books: Fiend Folio, Libris Mortis & Lords of Madness

You need to choose a type of symbionts and some are race restricted.

A Changeling with the Racial Emulation feat can be interesting to bypass some of the racial restrictions. Other option would be Polymorph any Object I guess..