Small leasing business model forecast

[hanasamomo]

Hi, I am trying to use excel to forecast the financials for my small newly found business, but I came across a problem and would like to get your help.

Here is the simpler explanation of the business.
1. I spend 100 to purchase a computer at the beginning.
2. I lease it to a customer and get paid 10 every month for 12 months.
3. By the end of the 10th month, I will make 100 and purchase another one and lease it in the 11th month.
4. By the end of the 18th month, I will make 100(20 from the first customer and 80 from the second), and I will repeat purchasing and leasing.

What I would like to achieve is to make cost of purchase, leasing period in months, monthly fee variables and then create a forecast sheet.

So far i don't have any clue and appreciate your help. I don't have any knowledge around vba so is there any way i can do this by only using formulas?

Thanks,

[FDibbins]

Set a small workbook with some dummy entries, and show us how you would do this manually.