Well I hate to crap on your idea, and trust me, I wish I could say go for it, it'll work... But I can't.
Outbound is brutal which is why almost no one does it.
And I hope you're a good great fantastic salesman and have a good great fantastic pitch. You're walking into (or emailing or calling) a business trying to convince them to buy a high priced domain name when they already have a different one they paid $15 for (or none at all). In either situation, even if you convince them and they like the domain, then they start thinking about how much time and money its going to take. Issues such as rebranding, building/rebuilding a website, setting up new email, changing every piece of printed material such as signage, business cards, advertising, menus, etc... Then by the time all that clicks in their brain, its probably a big fat "ah forget it, the domain I have isn't that bad after all".
By waiting for serious inbound inquiries, they are already past those hurdles and they're mostly ready to buy. The only thing preventing you from a sale at that point is agreeing on a valuation/price (which is still a big hurdle).
If you don't need money (i.e. living home with the parents for the summer), then sure, you can probably go without the usual summer jobs.
But if you need money and really want to try outbound, I'd suggest doing 90% at a day job, 10% domaining. If your domaining efforts are making more than 10% of your income, then start working less at the day job and more of the domaining. That is ONE nice thing about domaining, you can do as little or as much of it as you want, so if you're methods are working, then you can slowly ramp up.
