I did by buying EXAS when the new CEO came in at about $2. The previous management didn't have what it took to get it off the ground. The availability to buy the test came out this quarter so sales numbers are not in yet (but it is fully reimbursed at ~$500, where management said they would make a killing at $300). So after doing your due diligence, it may be worth waiting for the sales numbers to come out and buy on any weakness.
The other way to take advantage is to get yourself screened :)
