How much WBL should a player invest in their mount/companion(s)?

[Tipsy_Pooka]

Just a general question I wanted to post to the playground... I have seen a lot of optimization about how to get the BEST mount/companion by level.. just very little in how to invest in any equipment/items them after that... especially when the use of said mount could be situational (e.g. no availability in urban/dungeon missions).

To be clear... I'm not looking for this to be an argument on the merits of any mounted vs unmounted build... just a general-purpose guide for those considering builds that include these features.

[noob]

It depends a lot on the set up.
Do your mount gets targeted a lot by mind affecting spells and have no source of protection against evil?
maybe the good thing would be to buy it an item which does that or get the caster to cast that spell on it.
If it is mind blank time and that you have no caster then you should get a magical item of mind blank on your mount to avoid death by scrying.