I have used a few different companies for proxy use, and I just wanted to share one of the better one's I've found. I started with PacketFlip, and liked their service OK, until people started abusing their IPs to shit and basically ruined it for everyone.
So the company I have been working with recently is called Your Private Proxy.
Pricing is pretty much normal, around $2/proxy for any significant number of proxies.
The functionality is great. My favorite part about the service is the user interface, which allows you to choose which GEO location you want your proxies from, and also has a function where you can actually swap out your proxies once per month if you are not liking the performance. I haven't had to use this function, but I do like that it's there.
The guy who runs the company responds really fast via email and so far, has been really nice and easy to deal with.
Here is my affiliate link:
http://www.earthlovesit.com/idevaffi...ate.php?id=109
And non-affiliate link:
http://www.yourprivateproxy.com
The proxies are good for scrapebox, classified ad posting, twitter, youtube, etc. The only things that are not allowed are xRumer, mailing, and, of course, completely illegal stuff like carding and underage p0rn, etc.
In my experience they have worked really well and the support is awesome too, if you need it.