I would make the case that 100k Avios is probably worth about GBP 1k - GBP 2k if it allows you to make a CW redemption you would otherwise have paid cash for.

If you already have a million or more Avios then I would argue that an additional 100k Avios is essentially worth almost nothing, at least in the short term, because you already have more than enough for a good number of redemptions.

However, never accept a lower salary for the Avios earning potential!!!