Learning to DIY is both frustrating and rewarding. Keep it simple to start and make lots of small batches to compare what works and what doesn't. Don't be discouraged by failure (learn from it) don't stop buying the odd premium juice you fancy (for inspiration), don't be afraid to ask for advice here and (above all) be safe. Keep a tally of what you spend and hopefully you'll still be ahead of the curve even with a stockpile of dozens of flavour concentrates you'll never use again.