Shit's expensive in the US too I use Jacks Classic and my buds are nice just as nice as overpriced nutes I tried a few then saw one dude SimonD or some shit with nice plants got me to try it I haven't looked back and it is cheap as hell and produces great buds.
before all the different bottled nutes were here in the mid 90s we only had the 3part GH food which is a rip off
or eco grow powdered food , i was pleased to see the eco grow is still on sale, i might buy some of that again just for the nostalgia
i was looking at optimum bloom but i cant find any info on it, there website (growth technology) doesn't give away much, that is the cheapest branded liquid food here
it is only £70 for 20 liter set A+B, sent them an email not heard from them yet on their NPK's etc
peace