I've tried the BlueLine compressor (free or almost free shareware) and I found it ruined any signal I put through it. I've had much better luck with Waves C1 for uncolored compression (RenCompr for colored compression). You should be able to get Waves Native Power Pack for ~$300 which also gets you the L1 limiter and TrueVerb. I recommend you download the BlueLine and compare it with the Waves Demo (14-days w/o any restrictions). See if you can hear the difference. I'm sure they're alot more free compressors, but I don't have anymore experience there. Good luck!