Well, first off. There isn't just one guy you can obtain leather strips and iron ingots from. Also it takes 48 hours [in game time] for the shops to reset back with new items. So just do the wait option twice for 24 hours.

There's only one location where you can get about 200 iron ingots, but it involves stealing. It's a museum in Markarth. I didn't even touch the museum when I was leveling.


What I did:

I start off in Riften buy iron and straps from him. Then go to the town of Riverwood do the same. Finally head over to Whiterun hold and do the same. Now, once your finally in Whiterun create all the daggers and sell them to the blacksmith there.

Remember to wait two days!

Are you sure its the museum in markarth cause i didnt find any iron ignots there