Ways to boost item's caster level without increasing cost.

[Yogibear41]

Looking for all the ways to boost an items caster level without increasing the cost. For example if you make a normal wand of a 2nd level spell with base caster level of 3rd, using the Dark Speech feat you can increase the caster level of the wand to 4th level, but retain the normal base price of the wand. Feats such as Wand Mastery that only boost the caster level when you use the item yourself would be cool to know too.

[sleepyphoenixx]

Words of Creation has an option for that iirc.
Reckless Wand Wielder (CArc) boosts CL by 2 by spending an extra charge.
Cannith Wand Adept (S:CoT) adds his class level to wand CL and DC.
There's also gems you can add to wands in MoF to increase CL or DC which do add cost, but it's a fixed price, not a multiplier. Also since they're non-magical you can presumably reuse them.
Inspired Master (Dr#339) is a feat that adds +1CL to any item you use

Unbound Scroll has an ability to increase the CL of scrolls by expending uses of their Dragonmark abilities.

Somewhat related ELH has the (non-epic) Enhance Item feat which increases save DC by your ability mod for items you craft yourself.