Google doesn't block or penalize ip's they do domain names, so unless you are trying to cheat Google with a bunch of bogus circle trades there is no point to get a dedicated ip unless you need a ssl.
If you want to rank well like we do
then find real link trades and keep working hard on it, end of story. And stop listening to people that don't have any top listed sites for substantial amount of time.
We have plenty of i.p.'s to last the next ten years, but I prefer to keep it real.
Dedicated IP's are needed for ssl and that's it.