Yes, I think your 6.84 is in the ball park based on present information. With respect to the post-earnings price move it's difficult to get a sense of investor expectations with DAVE. There are probably a lot of people who have been sitting on dead money here for a while and wouldn't take much encouragement to sell if the call disappoints.
On the other hand, DAVE's cap is so small, and so few shares change hands every day, anything, positive or negative, could move it 5-10-15%. Like you suggest, a new share buyback would be a positive driver.
Therefore, while I agree with you generally on valuation, I think the price after earnings could go either way, depending more on what they say in the call than anything else. The economy, consumer confidence and above all, unemployment is a real problem but at some point it gets baked into investor expectations. I don't know if DAVE is at that point now.