I remember seeing it pop on and going "no way, that's priced ridiculously high."

Rent growth is a function of supply, demand, and interest rates:- I'd ground any forecast by stating I expect national rents to rise on a pace more or less in line with inflation over any long time period. 2-3% per year.

NAR Says - Existing home sales fall to lowest level in nearly 30 years and Median housing prices rose to a record high"The National Association of Realtors released data that showed existing home sales declined to the lowest level since 1995 last year, with 4.06 million homes sold on an annual basis.Meanwhile, the median home price median home price rose to a record high of $407,500 in 2024."

How do you value a apartment that will be rented out to primarily section 8 tenants?  

While I’ve considered cash-out refinancing or HELOCs, the high rates make these options less appealing.I’m debating between using cash to acquire more SFRs or diversifying into mixed-use retail properties.

Ask your PM how to come up with some strategic incentives...possibly listing high and reducing every 7-10 days until it's rented, offer a move in special, a gift card, future rent credit, etc. 4.

The house includes high-end upgrades such as custom cabinetry, granite countertops and energy efficient appliances.

For example, if you have $130K in equity, you might get $100K-$110K available in a HELOC.Look for a fixed-rate option for the HELOC to avoid rising rates.

So I could hypothetically include a studio apartment above the garage and rent out the main house and be within the law? 

Honestly with an interest rate like that you could even not pay off your primary and put any excess capital in a high yields savings account and be financially further in the long term.