I personally make my own from pure isolate so I can't recommend any specific product unfortunately, I just noticed that a few if their prices were good. HornyFlava and Tasty CBD at 2500mg seem very well priced on both ecigone and vapestreams, but I would say do some research into these brands. It could be the quality or the quantity or that it just doesn't have much of an effect on your body, its hard to say really as everyone is different... I know thats not a very helpful answer but its one of those things which is trial and error. To give you an idea as what is helpful to me, I currently vape 10mg per ml in mesh sub ohm devices such as the big baby beast and that is helpful for me (I suffer from a bunch of mental health issues including insomnia so I feel your pain mate). So yeah just gonna be a little testing on your part I think, I know it sucks because of the cost to test CBD products. You can't overdose on CBD so maybe just go to town one night on a reputable product which has a lab sample sheet and see if CBD is helpful to you. Hope that helps.