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To me all this is fun (pure geek) so its really just desiding whats going to make me rich

I assumed I was the only one that thought linking was fun.
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Is this a good idea, and can anyone recommend any good sites if it is?
I agree with what's written above about buying links to boost PageRank - but - will admit to using the meter of green as
one of my criteria when buying links.
I say buy the links if they'll benefit your site and it's marketing goals, you have the money to spend and the resources to monitor them.
Before you plunk down any money, do a little checking to be sure the site you're going to pay attracts visitors that buy your products. Any site that won't share it's stats with you regarding this kind of info is one I'd avoid.
Niche directories are a good option, they are usually very economical and have relevant visitors. Go to the category where your link will be housed and backlink the sites listed there. Do they show the directory in their backlinks? If they don't, you have a decision to make. You can visit a site like the ISEDB.com for a list of directories or pay a directory submission service. (why..... I know of a good one!

)
Another suggestion - visit a blogging search engine such as daypop.com and search for blogs in your niche. Once you find them, look at their advertising terms and find a couple with high traffic and popular in your demographic. Blog advertising is usually less exspensive and with more and more journalists and content development people using blogs as an info source, advertising on one in your niche is smart.
Hope those recommendations help. And Happy Holidays to you too!