The floor for a whole building with a recognizable corporate tenant and long term is realistically $1M to $1.5M, and at 35 to 40% down that's $350k to $600k of equity plus $15k to $25k of diligence and closing costs. Hollow is right that the small-market discount stores sit at the bottom of that band. Nothing about owning one requires a license, by the way. You need an entity, insurance behind the tenant's policy, and a lender if you're borrowing.
The smaller paths people actually use, with what each costs you.
A DST, or Delaware statutory trust, sells fractional interests in net lease property. Minimums often start near $100k, it's a security sold by licensed reps, you have no control over anything, and sponsor and ongoing fees are real and disclosed in the offering documents. Read those documents with a professional who isn't selling it.
A publicly traded net lease REIT gives you the same tenant credit exposure for the price of one share, with daily liquidity and no diligence bill. What you give up is the direct ownership, the depreciation and the control over which tenant you own.
A partnership with two or three other buyers on one building. Cheaper on paper, and if you're taking passive money from people you don't know it can be a securities offering, which is a conversation with a securities attorney before you collect a dollar.
The thing I'd push back on is the framing that you're too early. Buying a weak tenant to hit a price point is how people get the concentration risk of net lease without the credit quality that makes it worth having.