Buy and sell as many as you want but just follow the google rules
So whether or not you philosophically agree with Google's point, if being in Google's search rankings is more important to you than winning an argument, Cutts suggests labeling paid links in the following ways:
· Redirect through URL blocked by robots.txt
· Redirect through URL using a 302
· Use Javascript to direct the link
· Apply the rel= "nofollow” attribute to the link
· Add <meta name = "robots" content = "nofollow"/> to the page header
It may not be fair to say that Google favors buying links from certain places, but there are "certain places" on the approved list, and they include:
· AdBrite
· Quigo
· IndustryBrains
· Microsoft AdCenter
· Yahoo! Publisher Network
· Any site that doesn't pass PageRank --THIS ONE IS THE IMPORTANT ONE
NOW PEOPLE THAT SWAP LINKS
THAT IS FINE AS THE SITE THAT LINKS BACK TO YOU USE THESE RULES AS WELL

Originally Posted by pirates

So whether or not you philosophically agree with Google's point, if being in Google's search rankings is more important to you than winning an argument

You're right, that's what it all boils down to at the end of the day.

Now all of the methods you suggested (or, really, Matt Cutts and Google suggest) will not pass along PageRank, but that's the point. Of course the benefit is that if a spammy neighborhood site buys a link from you, then you won't be penalized for it, even regardless of the paid links issue. So there really is a great level of protection afforded here.

I reckon, though, that if someone is willing to spend money and time on buying links, they could just as easily and with a better end, concentrate on building a great website and watching the decent links begin to point in by themselves.
I know we are all in a hurry to get traffic but IMO if you need to MASK something that you do, you shouldn't do it.
I don't say, "Let's all conform and obey!" but guys, concentrate your energy on making a **** GREAT SITE and you won't need to worry about masking paid for links.

definitely using paid links is for desperate people who badly want to gain fast results on their work.

Not everyone buys links to improve their search engine placement though. Many people buy links for the traffic they funnel to their sites.

Potential visitors might not be inclined to search for a selection of phrases that will lead them via a search engine to my site. But they might be inclined to click on a link to my site if they've been "warmed up" (developed an interest) by the page they're currently viewing on someone else's site. In this case that bought link has brought me targeted traffic I wouldn't otherwise have got.

I've just created a new product that nobody yet knows about, so nobody knows what to search for. But if I have a link that I bought on a related site giving a description of my new gizmo, the now interested surfer has a way into my site.

Buying links for advertising purposes is OK in my book.

Definitely agree with Gringo. And to go a step further, it's perfectly acceptable to buy advertising from companies other than Google. It's only when the "advertising" is meant not for direct traffic but for indirect search engine gain, that a line is crossed.

Whether people agree or not, morally, with Google's prohibition on paid links is less important than whether people like the benefits they get from Google.