I'm not in the business. But it seems to me that, if you don't already own most of the necessary tools, you might not have the necessary skills.
As for the inventory costs: if you're the only game in town, you might get away with ordering in parts as needed...But you would need a wholesaler account with a large supplier (or multiple suppliers). Here in the US, it would be a company called QBP; I don't know about Italy.
Also bear in mind that most shops make some of their profit on sales of new bikes and accessories. Just doing repairs will not be lucrative.
Last edited by Koyote; 09-19-22 at 01:21 PM.