A copy of a good cross-platform VST and VSTi host like
Tracktion is $150, and as many trips to
KVR Audio as you care to make are free.
At KVR audio you will find a mega market of every soft synth, soft sampler and soft effect out there with more being added every day. A whole bunch of them are free, like Synth 1, Superwave, Green Oak Crystal, RGC Audio Triangle II,
reFX Claw, and shareware synths are even more plentiful.
Free soft effects include the Kjaerhus Classic series,
Luxonix LFX-1310, BetaBugs stuff and many many more.
I've started an album project on which I limit myself to synths and effects available for free on the web, and so far have had no problems coming up with new and novel sounds...