This is a little bit on the grey hat/black hat side of the spectrum. But the fact is building a blog network with expired domains flat out works. The only issue is getting those cream of the crop domains without going broke. This video will walk you through tested strategies and techniques you can use to find powerful, yet affordable, expired domains.
I don't necessarily agree with some that dropped domains don't have value for SEO purposes but either way one thing you can do is to check out our tool for finding auction domain names (the tool has a database of domains available buy from GoDaddy and SEDO and also give additional SEO criteria to look up for the domains like backlinks, Compete data, CPC, Google stats, Alexa stats, etc. and there is also an option to schedule auction domain alerts so that you can be notified via email if a domain name meeting criteria you specify gets put up for sale) or you could use our tool fo domains dropping soon that shows all domains dropping in the next 5 days that way you can be ready to snap them up right away.
In theory, you could technically acquire a domain for $10,000 and be able to sell it for $100,000. You could also acquire a domain for $10 and be able to sell it for $100,000, $10,000… or $100, you get the picture. Because of this, it’s hard to recommend a perfect starting budget because your strategy, experience, and the pace at which you learn will hugely affect your buying and selling decisions.