I think it would be pretty rare you could do that in real estate. 

will also on the left coast its exceedingly rare that a property with improvements goes to tax sale ..99.9% of tax sale props are bare land. 

Combined rents on the property net roughly $4200/mo after expenses (PM, taxes, ins., etc.) 

Or any combination of these.

If your credit is strong you may be able to access an equity line for up to 95% combined loan to value. 

I pay myself and my wife a combined 120k/yr for this service (5-7 homes per year).2) My previous 19 SF BRRRR's are cash flowing 74k per year (P.I.T.I.) and in my current model, this Cash Flow is increasing by about 25-30k per year. 

These loans are structured with a combination of a first mortgage from a conventional lender (typically covering 50% of the project costs), a second mortgage from a Certified Development Company (CDC) backed by the SBA (covering 40% of the costs), and a down payment from the borrower (typically 10%).Bridge Loans: Bridge loans are short-term financing solutions used to "bridge" the gap between the purchase of a new property and the sale of an existing property or the availability of permanent financing.

And I am not privy to the transaction but I believe they are most likely paying market for the property.I think you will probably find it tough to line up a scenario focusing on just tax sale land. which is rarely prime development land.

as Update to this post from 6 years ago, there are heloc's on owner occupied 2-4 unit properties up to 89.90% CLTV or combined loan to values (meaning multiple loans but all together not exceeding 90% of the value).Terms typically areinterest only first 10 years and drawable from the lineyears 11-30 its Principal and interest payment Prime index/rate + margin (this portion is fixed but prime is not)underwriting is done assume prime + margin + 2% stress test for underwriting meaning if your prime + margin was 10% then your underwriting rate used to determine your maximum line you can qualify for would be 12% rate as an example based on principal and interest payment over 30 years or 360 monthsIncome is the main determinant of your qualification and fico min 680+ is just the min score to get through the "front door,"Maximum DTI or debt to income allowed is 45% DTIMaximum lines on this product go from 500-750k so you can get a decent line size that can actually buy other BRRR's or fix flips and deals.

They usually respond within an hour or two, but I rarely have questions for them.