I was wondering if there's a reason to purchase a commercial starter versus making your own. In theory the former gives you a head start on a healthy starter, but is it more often a waste of money?
Unless you have seen the active starter (like a baker or friend showed it to you), I wouldn't spend money on it...I also think it's much more satisfying to build one from scratch, it's not that difficult.
I don't have an in-person helper, and it was before I discovered this web site, so I decided to purchase a dehydrated starter. I was willing to pay for the simplicity and avoid confusion and some unknown factors. I was willing to pay for the "known quantity" factor.
The going commercial rate is $10.99, amazon or elsewhere. However, volunteers at www.carlsfriends.net will send you some dehydrated for a S.A.S.E. and a $1 donation. I got some of theirs, and it doubled on the fourth day of feeding, could raise a loaf on the 7th day, but didn't stabilize or "balance out" until maybe the 10th.
If you can upload pictures, you can get online help here, if you want to go the full DIY route.
If you choose to DIY, whole rye flour (such as Bob's Red Mill) seems the surest bet to get started initially. 2nd choice is whole wheat. 3rd choice is white flour (preferably unbleached). Regular feedings after initial creation can be cheap white flour.
Bon chance, bon apettit!