Don't believe the lies you may here on the forums (Especially post 1.0.3b) you can find lots of great stuff in the lower acts for example:
That belt was found by me last night in Act 1, as of writing this (7/2/12) it is the best Wizard belt on either North American auction houses
What makes it better than the one other belt with slightly higher vit and int you ask?
This belt has about 400 more armor and Physical resist, that belt had cold resist (Cold resist is not a primary resist, physical is the best resist, 264 armor, no +Armor and only 4 affixes.
Don't give up if you cant farm higher acts, sure act 3 is awesome but it is only slightly better than act 1 inferno and your chance of death is a lot higher meaning less potential profits.
(Sold this for 27 Million, so yeah you can find awesome stuff in any act)