This market has very low barriers to entry & this has resulted in many people setting up classified apps, only to fail to gain traction. I've seen literally hundreds of people attempt this over the last 5 years and fail.
Advertisers won't place ads with you unless they see many listings on your website and / or have heard of you from some credible source, they will place ads where the most amount of people are likely to see them and these days that still means craigslist or ebay for most people.
What is going to be unique about your app?
Why would I place an ad with you vs craigslist? Esp when they are free and drive good response rates for most people.
Asking someone to actually pay for a classified ad is a big ask these days when there are so many free & popular options out there.
If this was me, I'd forget about running my own classifieds app and instead provide a platform that will allow other people to start & run their own classified apps - kind of like a shopify solution except for the classifieds space.
For example:
1. Use targeted advertising (Facebook Ads, etc) to attract more of your best customers.
2. Use tools like visualwebsiteoptimizer.com to test and optimize
3. Find ways to sell your by products [http://37signals.com/svn/posts/1620-sell-your-by-products]
I wouldn't worry too much about the "1.0-ness" of the site. Most users (especially in your niche!) don't care about bleeding edge technology and are even sometimes turned off by it. I know dozens of people that love freecycle and none of them ever said "I wish this had more AJAX and shiny tables!"