I just recieved a response email from an agent!

I'm a bit stoked that I got a response email back from a Remax realtor after posting all my criteria on Trulia.com. I wanted to see which agent on there would bite and sure enough I got one to respond. The agent sent me an email saying he has some listings put together for my area and asked me what is the top dollar I'm willing to invest? How do I go about answering that question? Any advice is greatly appreciated.