Making your own oils can be very practical if you have the right equipment and supply of material. Vacuum distillation of lavender will pay for itself after a relatively short time if you make a lot of soap. This wasn't practical just a short time ago, but new equipment is making home extraction fun and effective. I get over 100 ml of pure oil extracts from a couple pounds of organic lavender flowers- unadulterated and just as potent as the most expensive oils out there. My machine pays for itself almost every time I make a large batch of lotions.
A lot of criticism is made of people who make their own, and it is ironic since these people know exactly where their product comes from, exactly how potent it is, and is often just as high quality as high end retail oils. The main difference is quality, price, and fun. I have learned a lot more about essential oils since making my own, I have a lot more fun making soaps and lotions, and I enjoy not paying the incredibly high prices for retail oils. I control the quality, and although I am not obsessed with the purest oils out there, I'd put mine next to any of the retail brands for comparison for use in lotions and soapmaking. I use an Extractcraft unit I got a while ago as a tester for them, and I hardly ever have it turned off any more. I only buy oils I can't reasonably or economically buy dried plant material to extract at home.
Making your own oils adds another personal dimension to your craft, makes it more fun, and can definitely save you money.