Small correction: the penalty on budget transfers is 100%, not 50%
To my eye, IFA scouting and prospect signing is the least efficient way to acquire talent for a franchise. I've heard many times how dominant teams can't rely on the draft anymore, but if a franchise has players talented enough to win regularly, then those are players that make better trading opportunities. And any team that's got a solid roster can also intelligently stock talent on the bench with an eye toward trades and draft compensation. Setting aside huge cash hoards for IFA scouting and shopping short circuits all the best roster and contract management strategies.
IFA shopping would be more viable if market forces didn't go so crazy as to make the total cost of a top IFA prospect $25M to 60M. (Scouting, maybe 10M, plus signing bonus of 15M to 35M, which could include transfer penalty of up to $15M in this example.) But at that price, the opportunity cost is very high. And this says nothing about the seasons in which a team is left sitting on 14M or more because the right IFA just didn't surface, or they got outbid for the 3 or 4 that were actually worth bidding on.