In addition, the cost to repair any given damage done to a property is relatively uniform over different markets (especially if you do the repairs yourself). 

Find comps that: have sold within the previous 3-6 months;are within the neighborhood geographic boundaries;have similar features;are approximately the same square footageRemember that the condition of the comps needs to reflect what the potential subject property will look like after rehab.I wrote a biggerpockets blog post on how to find comps and calculate ARV which may be helpful:https://www.biggerpockets.com/blogs/8814/68395-how-to-find-real-estate-comps-and-calculate-after-repair-valueReach out if I can help with anything.

The $60-70k rehab estimate seems high as I'm shopping for an Inglewood condo and some of the worst 2bed 2baths in the city wouldn't require over $20k in repairs/upgrades. 

We are buying our first list of 1,000 owners and need to append 1,000 phone numbers to go with them so we can follow-up call.

If the roof needs repairs they would handle that process and maintain the solar equipment.

and get them to give you the phone contact info of the tax buyer.

Or are they just dodging your phone calls, emails, and letters?

You can't build a relationship over the phone, and for sure you can't build a relationship with "Hi, your in foreclosure, would you like to sell" which is often the agents first question when they go after foreclosures. 

The following formula should help you as a wholesaler:70% of After Repair Value (ARV) - Repairs - Your Wholesale Fee = Your Offer PriceFinding people that are willing to sell their property at such a discount is the most difficult part, but if you can do it, the buyers will come from all over to buy it. 

You would use their money to purchase, and do the repairs as quickly as you reasonbly can, then go to your bank and get permanent financing (or get your whole mortgage as a HELOC if you can find a bank/credit union to give it to you that way).It'll cost you a few points to the hard money lender, and a 10-12% rate for the time you have it.