What i ended up doing was to throw away the models of the missions and make it by myself (i mean, 8k for recovering an ancient artifact?)
Missions Rewards are based about a low-power campaign, and even then the rewards aren't that bad in SR4. SR5's Missions rewards are also not bad, but with 1 big flaw: The runs give after Negotiation what the book says should be the base pay BEFORE Negotiation.
If you follow the base rewards the game system suggests, you end up with quite decent payment. The problem is that that means you actually have to design some default enemies and figure out what you'll throw at them, so you know what dicepools to base the rewards on.
But then again, that can be as simple as "they're facing at least 1 enemy with an offensive 12+ dice, and no enemies with an offensive 16+ dice" and "I intend to throw a lot of weak mooks at them in one scene", and you got the whole Yakuza-involvement and bam, x3 from the dicepools, x1 from the 3-to-1 outnumbered scene, x1 for the risk of a raised profile, and the base reward is 15k, with 500 per net hit (you'll want to set a maximum of 4 or 5 on that, with 4 it's 17 grand per runner.) So if you're doing Yakuza runs which involve either a lot of Critters in a scene, multiple Spirits usage or an attack by loooootsa weak mooks, your runs are likely to all be 15k + nethitsx500 and 6 karma.