I think so long as its a good product then it doesnt matter who you buy from. If they are safe and effective and custies like them - then stick with them. Suppliers have some great solutions available at good cost.
Personally we use our own product - which our clients really like and is more cost effective for us. Its a win win as custies often want more and we make a good mark up (approx 1400%).
Cheers
Kev