Prognosis: $$$$$You can check my posting history on this one. I admit that Im a booster from waaaay back and I am averaged out at about a buck on it.
It has been going gangbusters but for one little thing: profit.
Ok, profit is no "little thing" but the plan in place seems pretty clear. Acquire customers and then seek profit. "Monetize them" if you want to borrow a recently over-used term thanks to "The Social Network". The mere fact that the company can break even while giving a way a big chunk of their product for free to acquire customers cant be overstated enough.
All that has to be done is to determine when to start charging more for the product. For a recent example see Netflix. People cried out when they raised their rates by 60%, but the service will still be used and the market cheered.
Coastal sent out 500,000ish orders last quarter. That is a growing number. Even if you factor in no growth you are currently at about 2,000,000 orders per year. Find a way to get 10 measly more bucks (oversimplified, I know, but to suggest even $20 would not be outside of the realm of possibility) out of their current stable of customers and that' is another 20 million dollars, presumably a large chunk of it profit. Do your own math on what you consider to be a reasonable valuation at that speculation, but I think it'd be hard not to agree that under a wide variety of models where Coastal finally raises rates it will be worth a great deal more than it is now.