Based on prior knowledge and intuition, we can analyze the relationship between the feature "buying price" and the target variable "rate of decision to buy the car". 

It is expected that the buying price of a car would have an impact on the rating of the decision to buy the car. Generally, if the buying price is very high or high, the decision to buy the car might be rated as "unacceptable" or "acceptable" by some individuals. On the other hand, if the buying price is medium or low, the decision to buy the car might be rated as "good" or "very good".

Using this analysis, we can generate the dictionary as follows:

```json
{
    "unacceptable": ["very high", "high"],
    "acceptable": ["very high", "high", "medium"],
    "very good": ["medium", "low"],
    "good": ["medium", "low"]
}
```

Please note that for the target classes "unacceptable" and "acceptable", the buying prices "very high", "high", and "medium" are included. For the target classes "very good" and "good", the buying prices "medium" and "low" are included.