It's hard to give specific advice without specific information about your product, but here's the process I've used when pricing RateMyStudentRental.com for schools, and LeadNuke for businesses (note that my experience is primarily with B2B pricing).
1. Who is your target market? How much money do they have?
2. How much value do you create for them? <== This is IMPORTANT
--once you've set your price based on the above, continue to steps 3 and 4--
3. How much to related/competing products charge?
4. How much would you need to charge to be sustainable?
A few notes on these... The second step is by far the most important, but also the hardest. It's not about how much value
you think you create, it's how much
they think you create. Often, the simplest most trivial features end up creating the greatest benefits to the users. This can be difficult to grasp for anyone close to the product. In fact, this is the very reason you should start out pricing HIGH, higher than you're comfortable with, and refine the price from there.
Also, I try to set a price based on steps 1 and 2, before continuing on to 3 and 4, because 3 and 4 are really refining and validation steps. Step 3 is a good check to make sure you're in the right ballpark. If not, you need to go back and check your assumptions and figure out why it is you're so far off from the competition (although being far off is not a bad thing, just make sure you know why). Often, the very reason your price is so different from competition is because your step 4 may be vastly different (or wrong).
Step 4 is hard to do until you have a good idea of what your customer acquisition costs are, which is why it's also done after you set a price. The fact that you have 200 FREE users means you still know nothing of CAC. Step 4 is a very important validator of your business in general. If the amount you determine for step 4 is higher than the price you came up with, what you have is a problem, not a viable business.
Of course, my own process is a little more involved than this, and usually requires a lot more refinement (none of these steps are meant to be done just once).
Hell, maybe a good place to start would be asking some of your free users if they'd still use it if you increased the price to $X.
That being said, two of my favorite stories about pricing are the interview with Steve Blank called "It’s very easy to underprice your product" [1], and Jaques's recent post, "Double your price! (and no, I'm not kidding)" [2].
[1] http://venturehacks.com/articles/pricing
[2] http://jacquesmattheij.com/Double+your+price+(and+no,+Im+not...