It would also be quite possible to swing these rules in the other direction, bringing SW:A strike teams into the deep Underhive. Since all of this is decidedly "black ops" work on a possibly alien [if not Imperium kill teams] planet, treat any SW:A kill team as outlanders. They are deep beyond their supply lines, and attrition will be their biggest trouble - getting reinforcements and gear all the way to their base of operations.
1. SW:A teams are Outlanders: as such outlawed and can never buy off their guild price.
2. SW:A teams have a single base of operations which they can work, or can loot-and-move-on as any other Outlaw gang. They will need to scavenge, and fight starvation as any other outlaw gang.
3. SW:A teams use the Outlaws trade chart. If they save up enough to hire their incoming team member gets equipped from their list as normal.
4. "New recruits" start at 0 xp, "Troopers" at 20 xp, specialists at 60 xp, etc, parallel to House Gangs. Advances as per xp gained, rather than per number of scenarios.
5. Special Operatives are gang-specific Hired Guns, at the usual Hired Gun cost. Special Operatives which grant a prometheum cache reward have a 25 credit guild bounty.
6. SW:A gangs use the "guerrilla" skill tree and not the "tech" skill tree.
Yes, this does mean that Inquisitors, Space Marine Scout strike teams, and even Imperial Guard strike teams would have a guild price -- but they are far from the Upper Hive and any orderly supply and command chain, operating in a deep insertion mission. They can do it. Surely, they are not less able to survive in a Hive than some putrid xenos ork, are they? Thought not. Good.