For me, this "post HN" or "pitch Techcrunch" simply doesn't work. To receive HN upvotes you have to Show HN a product very specific to tech hackers crowd - my product is a product social network, I am sure no bootstrapped private social network would receive any attention here. Show HN small, neat, open source projects go much better than "try my product" Show posts. And for TC you would have to be much more high-profile than me. Like eing one backed by a famous accelerator, funded or a former early employee of Google/FB/Twitter.
What I am doing is dealing, progressively with three bottlenecks: visitors coming, visitors signing up and users coming back.
For the first one, Adwords is good enough. I spent $5 daily, receive about 300 clicks (1 or 2 cents CPC). This give me a constant flow of visitors to run the relevant experiments.
For the second one, I am improving right now. I have about 4% of the visitors signing up. I am changing my landing page and will do some tests to bring it, at least, 10%. Don't be tempted to focus too much on improving sign up rate right now. The only purpous of these 2 steps is to give you a good enough flow of new users so you can test your retention (or revenue per user) rate. Nothing more. The same advice for your Adwords campaign, create a good enough one, so some visitors go to your website, don't try to be a master of Adwords (for now).
And third, the goal of all your steps so far, retention (or generating revenue, I don't know your model). For me, having 30+ new users each day is enough for me testing my retentions with different tactics. If you need more than this, than you might raise your Adwords daily budget, or try a little more to improve your sign up rate. But fix your number of new users I just work hard enough to match this number.
When you have a good enough number of daily new users, than your work on marketing match with your goal to deliver value to your customers, and then good enough is no more enough. This is when you must excel on testing, iterating and improving your product. With no excuses as "only if people knew what I am doing"....
Good luck!
You can try to get bloggers and press but in my experience you get spikes of traffic and what you want is predictable and consistent traffic which you can run tests against. Getting 3k signups in one day from TechCrunch isn't terribly valuable, IMO.
You can buy it fairly cheap from Ads on Google, Twitter or Facebook. Try them all and see which work best for you. I prefer Google/Twitter. This is both consistent and reproducible.
Consider getting your first 10,000 users as more of a learning experience of what the hell you think you're building and what your customers think you've built.
I operate a wiki site and I literally spent years adding content, developing and refining to the point that it now gets a few thousand visitors a day. I am not selling anything and none of these people pay for anything or contribute to the site, they are just visitors. If you want a "brute force" way to attract an audience find an area you're interested in and make a content/tutorial/information site out of it. If you can couple that with something to sell you might have something. I haven't figured out the latter part yet.
Before launching publicly you should probably let atleast a few target users play with your product and gather their feedback .
1000 listings, and 50 dollars invested, would mean that even at a 10% conversion rating which I think is safe to say, for a fresh launched website is obscenely high, would mean you were paying 0.5 cents per click. (half a cent).
I don't think your advice is applicable to what the original posters wants.
Without knowing what exactly the OPs business is....
It's a poorly phrased question, 1000 (paying?) users, and retain them for what duration? Are you just wanting 1000 MAU, or just views... With 1000 users, depending on your signup, this could mean a factor of 1:20 of users to views. Both of which could be irrelevant to your actual businesses main metric which is sales?
To the original poster, try and clarify what you are asking...
To retain them. Constantly improve your product.