Here are some interesting articles discussing buying trading systems.Reading these discussions may help in understanding the failure risks associated with buying ready made systems
Trading is a very difficult job where 95 % of traders fail.75 % of accountants pass only 5 % of traders ever make money.The 5 % that make money are often dishonest traders working for investment banks , hedge funds and private companies.Some of the 5 % rely on insider information or some dishonest scheme in large institutions
A simple google search will tell you 95% fail.