What should one know before buying idols of Lord Ganesh and Goddess Lakshmi?

Traditionally, it's advised to buy separate yet matching idols of Lord Ganesh and Goddess Lakshmi in a seated position. Goddess Lakshmi should be seated on a lotus with one hand raised in blessing. Meanwhile, people should buy a Vamamukhi Ganesh idol, in which his trunk is tilted towards his left, as it represents his gentler form suitable for homes.