Psion Protection

[PaucaTerrorem]

Besides a high Will save what are good item/psion abilities to have on to keep psions from messing with your head.

[HaikenEdge]

Mind Blank.

[JeminiZero]

At lower levels, Protection From Alignment (http://www.d20srd.org/srd/spells/protectionFromEvil.htm) and Magic Circle Against Alignment (http://www.d20srd.org/srd/spells/magicCircleAgainstEvil.htm) all hedge out mind control (regardless of alignment of the would-be controller). My personal favourite is the Disobedience spell from Complete Scoundrel. Last hrs/level.

See if you can get these spells in one-off items such as potions or scrolls. Or if you want to use repeatedly, look up Drow House Insignia [Drow of the Underdark], Eternal Wands [MiC], and Minor Schema [Magic of Eberron].

Or if you can get them approved, as custom magic items of continuous effect.

[PaucaTerrorem]

Only issue should be that we're core/SRD only for base class, feats and most spells. PrC and some items can be from any official 3.5 material. Any racial items/spells/feats that I could un-racialize I would have to discuss with DM.

[Red Fel]

Well, let's head on over to the Lists of Necessary Magic Items (http://www.giantitp.com/forums/showthread.php?187851-3-5-Lists-of-Necessary-Magic-Items) for a look-see...

Ahh, here we are.


Mind Blank

Why you need it: Mind Blank protects you from two things - divinations and [Mind-affecting] spells. Being the victim of those means you're getting stabbed in your sleep, and made useless (or worse, hostile to your allies) in battle.
Cheap:

Continuous custom item of Protection from Evil/Good/Law or Chaos. 4000GP, head or shoulders slot? Following the magic item creation guidelines, this would cost 1 (Spell level) x 1 (Caster level) * 2000 (continuous multiplier) * 2 (Duration multiplier) = 4000 GP. This doesn't provide the full protection Mind Blank does, but it can effectively prevent you from being turned into a liability in combat. Worth mentioning due to being an order of magnitude cheaper than even the cheapest full Mind Blank item.
Command-activated custom item of Mind Blank (DMG). 43200GP, head or shoulders slot? Following the magic item creation guidelines, this would cost 8 (Spell level) x 15 (Caster level) * 1800 (Command word multiplier) * 1/5 (Once per day) = 43200 GP. The price is so low that I'd not allow the item myself, but you can use this as a starting point for your haggling with the DM.

Deluxe:

Third Eye Conceal (http://www.d20srd.org/srd/psionic/items/universalitems.htm#conceal) (MIC, XPH). 120000GP, face slot. More or less what it says on the tin - Mind Blank, all day.
Ring of Mental Fortitude (DMG2). 110000GP, ring slot. Gets you the mind-affecting immunity aspect, but not the anti-divination aspect.
Cortical Armor (Und). 146650GP, body slot. Mind Blank while worn, and a few side benefits that may be useful to some.
Cowl of Warding (MoF). 200800GP, head slot. Mind Blank, along with Freedom of Movement and Spell Turning. If you don't need the Spell Turning, it would be cheaper to get a ring for the other two effects.

Not Recommended

Eyes of the Spider (CotSQ)

[PaucaTerrorem]

Oh that's perfect. I should be able to work something from that.