The purchase window is Sunday

The developer’s Steam answer is direct about the timing: wait until Sunday. A player guide’s author separately confirms that, in the release version, having enough money when the landlord comes to collect rent makes direct purchase available; they did not need an extra special storyline. [1][2]

The important distinction is cash you can spend, not the estimated value of your inventory. Goods worth a large amount do not mean you can pay that amount to the landlord today.

Prepare, then use the landlord encounter

  1. Read the price in your run. Keep the purchase amount separate from the cash you still need to operate the shop.
  2. Have spendable cash ready. Prepare before the Sunday visit; do not count unsold stock as payment.
  3. Wait for the rent-collection encounter. Look for the direct purchase option in that interaction, rather than at an ordinary customer’s trading screen.
  4. Check the resulting ownership and payment state. Direct purchase and a mortgage arrangement are different routes. Do not combine a full-purchase figure with a mortgage’s weekly payments. [2][1]

Why the option might be missing

Situation What to check
It is not the landlord’s Sunday visit Wait for the relevant encounter. Having enough cash alone is not the entire trigger.
You have valuable stock but little cash Compare the displayed purchase price with spendable money.
You cannot cover the current price The interaction may only offer rent payment or deferral. Read the current options rather than treating their absence as a bug.
An online price does not match yours Check the guide’s difficulty and timing. The cited challenge-mode figures are not universal prices.

The cited guide’s 36,000 example applies to its challenge-mode conditions and period. Use the landlord’s actual quote in your game. [2]