Frankly, this isn't the sort of thing you can deal with through closing loopholes in the law regarding data purchasing.
Because it'd be trivial to avoid, just ask your pal in a friendly but foreign intelligence service to purchase the data and share it for intelligence coordination purposes. Plenty of laws protecting your own citizens from your own government, sure, but there are very few governments who extend any such protection to other citizens from other nations so long as they aren't on your soil.
Only way to deal with this is by thoroughly regulating data collection by anyone and enforcing those laws.
Because it'd be trivial to avoid, just ask your pal in a friendly but foreign intelligence service to purchase the data and share it for intelligence coordination purposes. Plenty of laws protecting your own citizens from your own government, sure, but there are very few governments who extend any such protection to other citizens from other nations so long as they aren't on your soil.
Only way to deal with this is by thoroughly regulating data collection by anyone and enforcing those laws.