I have bought some starter before but it was a con and totally unnecessary. Let me give you courage. Imagine your own natural grown starter. The article I read debunked everything.

All I did was put a quantity of rye flour into a bowl and added the same quantity of water and mixed it. I put a hotel hair hat over it to keep stuff off but let air in. I did nothing until I saw a bit of action after around .... I dunno .,. about 6 days or so. It started to let off some gasses you could smell. Then I simply added some more flour ...around 50 gms or so and the same amount of water and mixed. From then on, I simply added a bit of both if it looked hungry ie started to quieten after bubbling. I think you could give it a feed and put it in the fridge to sleep a bit when you travel. I reckon it would work a dream. I think the doze would mature and improve flavours and you certainly wouldn't kill it. I've been doing that with my poolish/bigga when making starter for baguettes and pizza and it adds flavour.

All the precise stuff is rubbish. I don't think it is precise at all.

Have a go. It is rewarding. I'm going to let my first loaf mature for a day or two. I'm sure it will tell me when It's ready to be baked. I'm going to use steam.