So flametongue weapon gives you 211 spell power per weapon so a dual wielding enhancement shaman gets 422 off the bat. Since you'll probably also have enhanced weapons that's another 30% for 274 and 548 total.
Using the only one handed caster mace as an off hand the Cudgel of Saronite Justice
Code:
Binds when equipped One-Hand Mace
42 - 137 Damage Speed 1.40
(64.2 damage per second)
Durability 90 / 90
Requires Level 77
Equip: Improves haste rating by 50 (1.89% @ L77).
Equip: Restores 13 mana per 5 sec.
Equip: Increases spell power by 281.
Means you'll have 555 spell power in your off hand and since its BS made it'll be easy to come by.
Lets use another BS created item for the main hand the Titansteel Guardian
Code:
Binds when equipped
Unique-Equipped Main Hand Mace
99 - 316 Damage Speed 2.50
(82.9 damage per second)
+58 Stamina
Durability 105 / 105
Requires Level 80
Equip: Improves critical strike rating by 29 (0.56% @ L80).
Equip: Increases spell power by 490.
Meaning you'll have 764 spell power in your main hand.
Enchant both with Exceptional Spellpower for an extra 100 spell power.
Code:
Enchant Weapon - Exceptional Spellpower
5 sec cast
Tools:
Runed Cobalt Rod
Reagents:
Infinite Dust (10), Greater Cosmic Essence (2)
Permanently enchant a melee weapon to increase spell power by 50.
Requires a level 60 or higher item.
From weapons alone you'll have 1419 spell power and just collect a nice caster off set and you're done. Fun shock and awe for all even if you miss out on the talents that make it gravy.