Bicycling may be the ultimate acid test for waterproof/breathable rainwear. Where I live, near Seattle, the topography of endless rolling hills really forces a jacket to perform, as you're hot on the uphills, cold on the descents, and maybe OK on the rare flats. I should also add that most waterproof jackets fail, in the sense that they can't vent fast enough. Even some of the highly breathable "water-resistant" jackets don't handle these conditions all that well. I've had above-average luck with Activent, a Gore fabric that's pretty water resistant and very breathable. Short of hard rain, it'll keep you dry for an hour or two. It's no longer made, but is marketed by Gore under the Windstopper label, featuring in the Concurve line; the Windstopper Balance Jacket sells for $119 (www.gore-tex.com).
I've also heard a lot of good things about a fabric called eVent, which is chemically similar to Gore-Tex but with a different internal structure that supposedly allows much better breathability, while still retaining full waterproofness. Pearl Izumi makes a terrific-looking cycling-specific jacket called the Channel Jacket ($200; www.pearlizumi.com) that uses eVent, although this is a men's jacket so you might need to improvise with a smaller size.
Performance, meanwhile, is selling its two-ply women's Gore-Tex jacket for a mere $170 (www.performancebike.com). This gives pretty serious weather protection, but its underarm zips and full front zip should give you enough ventilation to stay reasonably comfortable. Plus, it's worth it at that price.