My IDP Dynasty league uses a cap of $250. I am not sure what you are looking for though. Is this a startup? I don't think there is anything that could list a "value" for each player. League scoring and parameters are so varying that it would be near impossible to come up with something inclusive like that. I would think it would be more beneficial if you could assign a value to each position based on your scoring system and how many of each spot are in the top XX players based on roster sizes and starting lineup. From that you may be able to give a range for a roster position and then use that as a guideline to allocate funds for the auction.
We had the $250 cap from the start. The salaries were based on the original start up auction. Whatever the winning bid became the salary. Since then we have a fixed salary for draft slots by round. We also have a Restricted Free Agent auction every year and that sets salaries as well. We let the "market" assign salaries by having most veterans eligible for the RFA auction each year.
In addition if a player is on an expiring contract they are eligible for escalation if they finish in the top 15 of their position for the current year. They then escalate based on their finish and that becomes the new salary if the existing owner wants to continue to keep that player.
Trying to assign a salary for players already rostered after you have not had salaries is difficult. My suggestion would be to either assign based on performance (RB1-5 = XX, RB6-10= XX, etc) or assigned a dollar value per point scored. I really don't see another fair way to assign salary as it should be based on actual performance.
Any player you get in the draft or auction is eligible for up to a 3 yr contract. That fixes the salary at that price for those years so they aren't eligible for escalation if the player finishes in the top 15 of their position in a given year. Once the contract ends you can give a 1 yr contract (basically keep them one more year) at their escalated price. You can do that forever although the salary has a chance to keep escalating every year if the player performs well enough to be a top 15 scorer at their position.
If you decide not to keep a player under contract you get hit with their remaining contract salary against the current year's cap. So if a player had 2 yrs left at $10 per year you take a $20 cap hit to cut the player. Also, the salary cap is only for freezes/auction at the beginning of each year. In season there is no salary cap to allow for easier trading. I would highly recommend that to make trading easier. It's hard enough without restrictions so making it as easy as possible is always a good idea.
The theory of allowing a multi year contract to drafted and auction acquired players is that all teams have the opportunity to get that player so if you get them you can give them a contract. Players you have the rights to and never let them available to the public has to be subject for escalation so you have to pay to keep a good player for longer than 3 years.