I built 6 spec homes for an investor last April through June. 3 of them in 1 town that sold while being built and he profited 60k a house. The other 3 where in a different town. 1 sold 1 month after completion and made around 50k and the other 2 just closed this past November and he just barely broke even.
The 3 that sold in 1 town was bought as 1 lot and sub divided. The other 3 in the other town where bought with shacks on them and demoed and built new.
That's why I said broad question. There's so many variables on how you buy your lots...knock downs. Size of homes you put up. The finishes you use. Ect. I never built a spec house but plan on it one day. Currently I just build new homes for people.