I use frontline spray on my cats. The large bottle, 500ml, is £70 from my vets! I looked online and could get it for around £35-£40 plus postage, but needed a vets prescription. So, I rang up my vets, they said they could give me a prescription no problem, it would cost £7. But, they needed to see one of the cats first, and the appointment cost would be £24! So with the cost of the appointment and the prescription, I might as well just buy it from the vets!!
I done a little more digging around, and found the spray on a french website, no prescription needed, it is exactly the same as I would buy from the vets or in the UK, for I think, £45 delivered! It was here a week later! I can try and dig out the name of the website if anybody wants it?
xx