Well, technically it's not "illegal" (against the law). It is annoying being on the receiving end of spam - you might end up sending spam to the wrong person on the wrong day and they could cause some serious reputation problems with your name, brand or company.
If anyone in this day and age still has a naked email which can be scraped, well they are already getting spammed. To stay in compliance, from my understanding all you need to do is have an REAL "unsubscribe" link. Unless something got updated, and changed.
Since it's un-solicited you'll need a lot to get any decent conversion. Now is it against Elance's or one of the sites which you are scraping TOS (terms of service), most likely, so there could be consequences from them on your end. As with everything black or gray hat, use pre-caution.
If I were you, I'd try a different marketing method which has not been killed to death. For example, you can do some real marketing and create a small business/marketing tip Linkedin group, a Google+ Community, and a Facebook Page. Then solicit people to join under the guise of "giving free marketing advice", or "free business advice", and "giving out free resources weekly". As the community grows, you can start dropping your link to your project every now and then, and remind everyone if they want to sign up, as a member they'll get a "discounted" rate. (The discount can be the real price - just up the price on your main site in case they go to it without a membership).
You'll make better and more longer lasting connections with an approach like that versus straight spamming people, since you are giving perceived value away in exchange. You'll soon notice, you have a growing following of people looking for your next advice, and can then turn it into your own CPA (cost per acquisition / affiliate marketing) platform channel for you, where you are pushing other marketing and business offers that you get a commission off of.
You can then take it a step further and go to brands, companies, and strike a deal for recurring commission off of your specialized push of their stuff, or whatever you want. You give them the opportunity to get in front of your growing audience - all while giving your audience a reason for staying - by sending them free marketing/business advice and new specialized offers.
I can keep going on... but I think you get the drift. If you do go down your spamming route, just remember "The best blackhat looks white" and "The best spam doesn't look like spam".
Carry on...
