simply go for different Sales order type with specific number ranges & maintain price accordingly based on the document type. This requirement is unusal & may not give consistent results. hence to be safer, play with the standard approach.
| Order type | number range | Price based on order type |
| ZA | 01- 99 | 500 |
| ZB | 100-199 | 1000 |
| ZC | 200-299 | 1500 |
| ZD | 300-399 | 2000 |