I use/used shared proxies for Twitter and i've never had a single issue, because of the proxies.
Obviously dedicated proxies are more safe, because it's only used by you until you pay for them, but those aren't virgin proxies either.
What's a good price?
With the provider i use, 50 shared proxies cost $25/month, dedicated is double the price. I think it's an ok price.
However not too long ago i saw 200 shared US proxies for $20/month with a different provider, now that's what we can call cheap.![]()