I've been making my own laundry detergent for several months now, and it's working fabulously. Not only is it cheaper and more environmentally-friendly, it's also more effective than the cheap supermarket-brand detergent I was using before. It's removed tea and tomato stains without any additional stain removers! Well, almost. I can just make out where they were, but they're barely visible.
It's so easy, as well. I haven't been able to find borax yet, as it's not in any dictionary I've found, but I've been using a combination of grated soap and washing soda. It takes about 5 minutes to make up a new batch, as I've just done, and a new tub-full will last about 3 weeks (it's a small plastic tub). I'm experimenting with using less and less of the detergent, and it's still cleaning effectively, so I might be able to make it last longer.
The only problem I've had is that I really notice the absence of fabric conditioner, but I've read that vinegar can work well. I've tried apple cider vinegar but it seemed to stain the washing machine (according to the landlord, anyway), but perhaps white wine vinegar would work. Watch this space!