Apart from the usual factors which affect price (like species of wood, or solid wood vs engineered wood), other factors include:

- dimensions of the plank (thickness x width x length). Many suppliers have max length of 3' to 5' - these are the 2nd tier cuts from the log and hence a bit more affordable. 18mm is fairly standard thickness for solid wood. When I did my floor, I specially use higher grade planks 19mm thick with max length up to 12'.

- sub floor preparation, namely the battens. What wood they use and spacing. Good standard is chengal and about 6" center-to-center spacing.

- what coating they use. I believe water based is more expensive.