There will be a difference in price between B&M stores and online vendors as the former have extra overheads. As I see it, it's the vendor's prerogative to charge whatever they like and my prerogative to choose where I buy. If a vendor can make a living and get any sort of market share charging R75 for TFA when it's available for R25 elsewhere, more power to them.
Regarding your recipe, is it your own creation or adapted from something else? 7% TFA Lychee strikes me as too high and I certainly couldn't vape anything with 2.5% Koolada. I would also tend to avoid additives like Ethyl Maltol and Sour. While they have specific applications where they can help a juice (like a leeeetle bit of EM to take the harsh edge off citrus), they are far more likely to mute/ruin it. At least, for my palate. But palates differ. I have seen recipes with % that are just bizarre. But many people like them. So it's a case of finding your happy place and mixing for your palate, not someone else's.
Regarding your recipe, is it your own creation or adapted from something else? 7% TFA Lychee strikes me as too high and I certainly couldn't vape anything with 2.5% Koolada. I would also tend to avoid additives like Ethyl Maltol and Sour. While they have specific applications where they can help a juice (like a leeeetle bit of EM to take the harsh edge off citrus), they are far more likely to mute/ruin it. At least, for my palate. But palates differ. I have seen recipes with % that are just bizarre. But many people like them. So it's a case of finding your happy place and mixing for your palate, not someone else's.