If you shop around you can get the Coopers kit for £63.98 with free shipping if you spend over £65, so add some steriliser and there you go...
If you actually work it out, the other items in the kit add up to £48.03 (online prices) so basically you are getting the FV for £15.95.... As far as I know the Coopers FV is only available on its own in Aus from the Coopers online store at $49.90 (£27.46GBP).... so its a bit of a bargain if you buy the kit and end up with some extra spare bottles and a beer kit to boot!!
"Best Deal"... well you have to take quality into account with this, the cheapest is not always the best, the old adage "You get what you pay for" is the case, I have 7 FV's and out of all of them the Coopers is (for beer) about the best. Though if I had the money I would go for a Speidel Kellermeister 30 Ltr Conical FV... Have seen one of these and there are the Dogs...
Also (though not at the minute) you can get the Coopers kits from Tesco online on special at £52, depends if you want to wait or not..... I am keeping my eyes open and will be getting another without doubt...
Also on your comment about plastic bottles, I also was never keen, but that was based on using them over 30 years ago and having all sorts of issues, when I used to brew with my dad... I have to say the Coopers bottles work great. Not had any problems at all with them. No leaks, no gas loss, lightweight and easy to clean. The caps can be reused and no need to buy new ones each time.. But you can get them if you want a tamper evident seal every time you brew, or wish to gift them to others and want to look professional.
I also have a large number of Grolsch flip tops and TBH am moving towards the Coopers bottles instead.
Hope this helps...