Jan 23rd 2018: $10.87 for .com and $0.99 for whoisguard ($11.86 total)
29th May 2018: $10.98 (+0.11) for .com and 0.18 ICANN'T fee ($11.16 total).
So it's $0.71 cheaper without whoisguard. So that margin (increase in .com) probably covers the actual whoisguard cost, the $1 fee was pretty much pure profit.