A ton of great plugins come with any issue of Computer Music mag. If you buy the digital version, it only costs $5 (Apple News Stand/Google Play). You can then register your digital copy and get access to everything that normally comes on the DVD that is included with the print copy.
Some of my favorites are:
Dune (great multi-featured synth)
Enzyme (quirky wave-scanning synth that won several awards recently)
Barricade (excellent limiter)
Single Mault (subtle distortion)
Reverberate (convolution reverb)
Philta (low/high/band/notch filtering with very intuitive interface)
There are around 40 plugins that come with every issue, about half synths and half FX. It's the same plugins every issue, more or less, so buy any issue and you've got them all.
Full list is here:
http://www.musicradar.com/computermusic ... cts-571808