A monthly membership at BrattySis will cost you $29.32, but not if you purchase a 4 or 12-month plan. The cost of a 4-month membership is $85.00. At this price, you pay an average of $21.25 per month. That is a 28% discount off the regular price of $29.32. The 12-month plan for $199.00 however is the best deal. If you opt for this yearlong plan you’ll pay an average of $16.58 per month and save yourself 44% instantly.