Determining Home Equity

[Nolan Neu]

I'm a first-time homebuyer and investment property buyer, currently in the analysis phase while saving up cash for a down payment. I'm looking to purchase a multi-family property at a discount - the area that I'm looking at has very slow turnover with multiple properties being on the market for 100+ days even in this seller's market. My plan is to purchase it at a discount so I can use any equity generated from the sale to be used to fund the renovations and repairs, rather than going through private lenders. I am having trouble understanding how to appropriately evaluate the property's value - is it based on the current "market" value, the 2020 tax assessment value of land and improvements, or from a bank appraiser who would be used during the purchasing process? I'm looking for a good way to estimate the value so I can make an appropriate offer, hoping to BRRR it. Would any of the values below be a good estimate?

Numbers on the property:

current listing: 299,000

2020 tax assessment: 197,000

Zillow estimate: 252,000 - 299,000 (279,850 is zestimate)

Redfin estimate: 295,000

I'm working my way through the BP bookstore, but haven't gotten to any renovation books so I apologize if this question is easily answered in one of those books! Thank you!