You've got the beginnings of an interesting basic house model here but the comments that you're going to receive are the same ones that you're receiving on your robot thread: if you want to sell your models then you should at least UV map and texture them.
Look, it would take an unscrupulous person with a fair grasp of basic modelling techniques about ten minutes (using your screenshots as references) to replicate this model. A more honest person with similar skills could create an original equivalent from scratch in a similar space of time. For these reasons, no one in their right mind is going to pay $40 for your building. This is not what you want to hear, I know - but it's the truth.
Look, it would take an unscrupulous person with a fair grasp of basic modelling techniques about ten minutes (using your screenshots as references) to replicate this model. A more honest person with similar skills could create an original equivalent from scratch in a similar space of time. For these reasons, no one in their right mind is going to pay $40 for your building. This is not what you want to hear, I know - but it's the truth.