My suspicion is most of these deals are lined up well before the deadline, and if the Phillies needed the additional allocations to sign someone they liked, they would have already obtained those allocations. I'm convinced from past seasons that they're skeptical of the highest priced guys most years and focus on landing multiple good bonus babies instead of one big signing (i.e. once past the top 2-3 players every year, you probably over pay for the next 5-10).
Notice they still landed 4 of the top 50, looking at past lists, the odds don't change much after a couple sure things - the variance in 16 year olds is so great you're better off going for volume (and you can't "break the bank" anymore). If they had been able to line up more top 50 guys, they would have found the money to pay them, they certainly have carte blanche to spend these days - but there are 29 other teams looking for talent.