Hi Kevin,
I'm new here and saw your post. While there is insufficient info to determine if it is a good deal, I will touch on some basic calculations you need to do.
Based on what info you provided I am making some assumptions to create a scenario.
Here's what you collect in rents: (assumption)
8 units total
4 @ $450
3 @ $550
1 @ $600
Total is $4050 a month; $48,600 a year
You need to figure out your expenses.
They pay for electric - I assume that includes heating and cooling. There are baths. Do you pay for the water and sewage and trash collection fees?
I expect there are some common areas that have lighting and cleaning/maintenance.
Property Taxes and Insurance. Do tenants have insurance to cover the contents of their unit and liability if they cause damage to the premises or other tenants' property. You may want to find out.
Since all units are occupied, you have no marketing costs for now. You need to review the leases to see how long they are and what clauses are built into them. It's good that you have tenants who have been there a while. They are not likely to leave unless you raise the rents well above market rates. You want to determine if their businesses are stable so they will be there for a while. Long leases are good; you know you don't have high turnover rates like apartments. Leases should have provisions to adjust the rents with market conditions within reason. There are many ways to structure leases.
I assume you have no employees - property managers, cleaning/maintenance crew etc. After deducting all the expenses from the rents, this is your NOI (net operating income) and does not include debt service.
Now you have to figure out your debt service. That depends on what you can put down. Asking price is $360K. 20% is $72K. Can you make a 20% down payment? If not, is the seller willing to finance part of it?
You need to finance the balance of $288K. Find out what interest rate you can get for a commercial property loan. As an example, 8%, amortized over 25 yrs, the monthly payment is $2222.83 or $26,674 a year excluding any points you have to pay.
Add the annual maintenance and other expenses to the annual debt service to see if you still have positive cash flow. You will have to change the interest rate and purchase price to see how the numbers change.
You also need to calculate the rent/square feet to see if it is comparable to other similar buildings in the area.
The CAP rate is frequently used to determine if the price is acceptable. CAP = NOI/Purchase Price. You need to find out for the type of building in that location what the typical CAP rate is. For the lack of a number, 10% is a rough guide.
Keep in mind that for commercial loans, although amortized over 25 or 30 years, the loan is for 3 to 5 years only. You will have to refinance at maturity. You need to determine if interest rates will be higher in the future and whether the rents will cover the higher debt service.
That's just the basics. If the numbers work out in your favor, it's probably not a bad deal. There are other factors to consider and you have not provided sufficient information. I suspect when you apply for a loan you will be asked to provide more detail.