Actually, you don't have to be 17th level.
Metamagic, Silent
Aura strong (no school); CL 17th
Slot none; Price 3,000 gp (lesser), 11,000 gp (normal), 24,500 gp (greater); Weight 5 lb.The wielder can cast up to three spells per day without verbal components as though using the Silent Spell feat.
Requirements Craft Rod, Silent Spell; Cost 1,500 gp (lesser), 5,500 gp (normal), 12,250 gp (greater)[b]
(Emphasis mine). If you look at the requirements, all you need is the ability to craft a rod and the appropriate metamagic feat. If you happen to find one laying around, the default caster level is 17, but you can make your own with a different level if you want to.
I have feeling that they used to require Wish or Miracle to create, which would explain the default caster level. At least in Pathfinder, that requirement doesn't exist.
Actually, you don't have to be 17th level.
(Emphasis mine). If you look at the requirements, all you need is the ability to craft a rod and the appropriate metamagic feat. If you happen to find one laying around, the default caster level is 17, but you can make your own with a different level if you want to.Metamagic, Silent
Aura strong (no school); CL 17th
You'd be dead on for 3.5, and are pretty darn close in Pathfinder, but the key is the new magic item creation system (released in a Web Enhancement back in the Fall.
Basically it now requires a skill check to create magic items, either Spellcraft or a skill related to the item itself (Craft(weaponsmithing) for crafting magic arms for instance). If you meet all the prerequisites, the DC is quite simple. What follows is the system I am using, based on the web enhancement and discussions in the forum immediately after (with Jason), and is my best estimate of the final system.
DC: 5 + Caster Level of item + 5/spell-prerequisite not met + *5/other-prerequisite not met.
*: What other prerequisites may be bypassed is not entirely clear, I believe feat-prerequisites specifically cannot be bypassed.
So, Basic DC for the rods would be 5 + 17 CL = 22. The Caster level is *not* a requirement, as it is for Ioun Stones or Periapts of Positive Channeling, so does not increase the DC. With 17 ranks + 3 class skill and a +1 intelligence, this would be an auto-make. At lower level it is more difficult.
Failing by 1-4 = Cursed item.
Failing by 5+ = Failed creation.
As to the original question, why is the caster level so high, I fully agree these are extremely valuable items, bypassing one of the key limitations on spell-casting.
Because they are powerful being able to add a metamgic feat to your spells three times a day without altering caster level, and in the sorcerer's case the extra casting time. All the rods are a great boon
Is it 3 times per day for all of the them or is 1 time per day for lesser, 2 times for the normal and 3 times for the greater? If not then what does lesser, normal, and greater do?
Because they are powerful being able to add a metamgic feat to your spells three times a day without altering caster level, and in the sorcerer's case the extra casting time. All the rods are a great boonIs it 3 times per day for all of the them or is 1 time per day for lesser, 2 times for the normal and 3 times for the greater? If not then what does lesser, normal, and greater do?
Well in the SRD at d20srd.org (which is free and easy to use) the lesser only works on spells level 3 and lower, the normal level 6 and lower while the greater works on any spell. Each do, in fact, work 3 times a day.