I have to agree with The Mighty Stu. So many things are coming to light about amino spiking and other short cuts the media will have a field day trying to scare unwilling people about the evils of taking supplements. The best advice is to stay with a company who values it's products and even more about it's customers.
Biotest is one that is not the cheapest but you get what you pay for. Remember it is going into your body. It is always better to buy one or two quality products then it is to purchase 4 or 5 cheaply priced items.