You have just make the adjustments with the content(changing the about us ,contact us information) to brand it for you.
The advantages of using this method is ,its economical,consumes less timing and effort than the custom programming methods.
The scope of business is broad and the interesting fact is the need of the service will grow with time.
Lets do the simple math, For every year there will be one out of 1000 in the population get married(whether its a Boy or a Girl). E.g India has the population of 120 crores(1200 Million).
These photos and astro profiles are storage consuming Recommendation Startup website- For startup website ,i recommend to start it with 5GB disk space plan.