As another take:
Although the ring duplicates only one 1st level spell, all of us agree that spell is a d@mn good one. So, price it out as separate powers:
- +2 Deflection AC (8000 gp)
- +2 Resistance Saves on Evil spells only: I'd say that deserves a 30% discount, as per restricted use => 4,000 * 70%= (2800 gp)
- Protection from Evil summoned creatures: This sounds like an entirely separate spell, actually (legacy issues not withstanding). How about a 2nd level spell, with a duration of 1 hour/level. If so, then the price for this power would be: 2 (2nd level spell) * 3 (min. caster level) * 2000 = (6,000 gp)
- Protection from on-going mental control: Again, this sounds like a 3rd level spell, with a duration of 1 hour/level. Cost (3*5*2000 gp) = 30,000 gp.
Then you must decide how "different" these powers are (given this is a "slotted" item). I'd say they are similar, actually, meaning that their powers are simply added.
30,000 gp + 6,000 gp + 2,800 gp + 8,000 gp = 46,800 gp
How's them apples?
Point being: it's one of those wacky "legacy" 1st level spells. Don't price it as a 1st level spell!