Also Reaper has a excellent bundle of plugins, that are probably some of the best for any DAW....
When it comes to buying plugins I'd advocate only getting ones which ones are needed, I myself anyway have found having fewer plugins to be more beneficial than having lots.
Right now I've pretty much reduced everything down to PSP ones; with Old Timer (for Compression), and sQuad for EQ. They might not give the extra 1 or 2 % of some more expensive choices but I find them really, really easy to use which I find to be one of the most important things.
Softube also make some great plugins and also for something a little more esoteric Soundtoys have some excellent plugins.