The values assigned to a driver in this competition are not a matter of opinion. It's all based on past performances and a mathematical formula. I'll do my best to explain it here. However a few points to note that may help with your selections.
Each rally will have a Number of Points Available which varies based on the number of stages and the distance of those stages. This is typically between 4000 and 5500 points.
The total value of all the FantasyWRC drivers entered into the rally gives us the Total Driver Value.
So if the Number of Points Available for a rally is 4000, and the Total Driver Value is 40.00, a driver is expected to score 100 points for each 1.00 cost. (4000 / 40.00 = 100). Therefore in this example a driver costing 2.50 needs to score 250 points to break even.
If the driver does better than expected and scores 350 points, they have scored 40% more than expected. The percentage gain is divided by 10 and applied to the drivers value. 40% / 10 = 4% increase. The drivers value will increase from 2.50 to 2.60.
If the driver does worse than expected and scores 50 points, they have undershot their target by 80%. 80% divided by 10 = 8% reduction in value. 2.50 becomes 2.30.
If a driver is not entered or does not start a rally their value is frozen until they next compete.
There is often value to be found on the entry list. Especially when the number of entries is low. This means those drivers in the support categories are more likely to break in to the points scoring positions. Additionally, if a driver is promoted mid-season from a WRC2/3 car to a WRC car they are likely to be underpriced, at least in the short term. The fundamental principals of FantasyWRC is to find drivers that are value for money. ie. They are likely to score more points that their cost suggests. If you pick the right drivers your team budget will increase in line with the drivers success which can then be used to buy more top class drivers in subsequent events.
There is also luck. You need plenty of that too.