Duplex has older furnaces and water heaters - question

[Mike Shemp]

Hello! I recently looked at a duplex and wanted to get some thoughts on if these items should be factored into the offer price:

The water heaters were over 10 years old, both gas furnaces were over 10 years old, the water was not separately metered, the front porch (cement) had some cracks in it, and both units would need some paint and new carpeting.  Also the pro-forma shows rents at $500/month, but Rentometer and other sites put the rent closer to $800/month.

2 Questions I was hoping the BP community could help me with:

1.  Should the offer price reflect the future rent potential, or the past performance?  The realtor keeps mentioning how the current rents are too low and it "could" get $800/month (he thinks).

2.  Should the offer price factor in that new water heaters will be needed in near future, the new paint, new carpeting, and front porch repairs that will be needed?

Thank you in advance for any suggestions!

Mike