Get the psion some magical or psionic full plate. Probably something like +4 full plate. Also get a +1 or +2 tower shield (if you need to squeeze out a bit more gold for other stuff, go with +3 full plate and +2 tower shield). Keep the primary hand equipped with a spiked gauntlet or a dagger, just in case; probably ordinary quality. Proficiency shmoficiency, psions can be bound in chains with only their eyes exposed and still manifest just fine (well, they might be uncomfortable enough in that case to need Concentration checks, but....). She'll be the Terrifying Tank That Flies And Shoots Liquid Fire. The attack penalties won't matter, and any form of psionic flight, telekinesis, and maybe freedom of movement, should obviate the need for any use of Str/Dex-based skills.
Also, get the psion a Headband of Intellect +2 or +4. Complete the package with a Cloak of Resistance (probably +1 or +2, since you'll be running out of GP to spend at this point), and maybe a Ring of Protection +1 or +2. An Amulet of Health +2 wouldn't hurt, but if there are Psioniatrices in the XPH, get a Psionatrix of Psychokinesis instead (I don't know if those were kept in 3.5; I only know some random details about 3.5 psionics differences). A few potions of Cure Serious Wounds, if any GP remains, should round it out I guess. I can't really think of many psionic items that both fit the psion type (kineticist) and the price range; there are some great psionic items that are much more expensive, but that's just the problem. :\