There are loads of little local bait firms that are around £5/6 kg. But chances are every angler locally is on the same bait....You can make a decent bait for around £3 a kg that will catch fish. And for £5 a kg you can make a top bait with quality ingredients. If I'm making bait, then I'm fishing. So I'd never factor in my own time as a cost as it would be one small part of a pastime that pretty much takes up all of my time. Also, you can tweak your own bait be it with ingredients, shape, size ,all the time to suit circumstances, most bait firms charge for this. I think if you're concerned about a few hours bait making being expensive, then you would probably have to ask yourself, How much does each fish I catch cost me? Basically, if you enjoy making your own bait and gain confidence from it, you will make it. If you're not really into it, then you'll probably look for a reason not to do it.
The first time I saw fish boshing over my home mades gave me a real buzz.