Any experience dropping price to gain rank, then increasing price to normal level?

[phonepro]

My app is around the top 100 paid in its category, but has had difficulty breaking into the top 100. Most of my success, I think, is just through having good keywords. I am at the very top for the search for my app and I believe that most people get to my app through the app store search. However, I want to get into the top 50, so that users will see it when they are browsing in the app store. I have had some success with dropping my price to gain rank, but then I lose rank quickly. I think, however, that this is because I keep the price down for too short a time (1-2 days), so that it doesn't have time to affect Apple's ranking algorithm. My understanding is that Apple's ranking algorithm is based on the volume of sales (not the gross revenue), and that increased sales increases your rank, but *sustained* increased sales keeps you at a higher rank even if your sales drop a bit. So I was thinking, if I drop my price to $0.99 or $1.99 to increase sales volume for a longer period, say 1-2 weeks, even if I take an initial revenue hit, I may be able to make it up (a) through volume, and (b) if I can keep a better ranking, then more people will see it at the regular (higher) price after I increase it back again.

Basically my question is: When you drop your price, sales increase. When you re-increase your price, how long do you keep your rank?