Growth rate will not stay constant, costs will not stay...

Growth rate will not stay constant, costs will not stay constant, basing your decision on a formula with so many variables would be worse than nothing at all.

Better of comparing to peer valuation and factoring in something you can reasonably calculate i.e sales for next year or so. Looking at peers 10 X sales is roughly a good guide market cap wise, and the company is getting close to reasonable value on a forward year 1 one estimate, who cares if they make profit or when they will, sales are most important now and growth in sales but you need factor in a reduction in growth rate rather than increase because always easier starting from a smaller base. Costs will become negligble in long term if sales execution is right.