Turnkey purchase price vs comps and LLC

[Warren A.]

Hi , I am new to real estate investing.  I am drawn to turnkey for many of the reasons mentioned on this forum (spouse and I have full time jobs, kids, not interested in DIY).   I have spent weeks reading many BP blog posts and forum posts on this forum.  It's been very educational. I am now trying to do some due diligence on on our first property purchase in Dallas (Everman, TX) from a very reputable turnkey company that is frequently mentioned/ contributes to this forum.

The purchase price of the property is $143K ($82/sq ft).  Net cash flow ~$400 /month.  It is going through $51K in rehab costs (new roof, more).   One thing that made me pause is Zillow comparable values are $90K-$100K .  I know Zillow is not the most accurate.  So I also checked Realtor.com and saw similar comps + median $63/square foot.  I don't know where I can find the actual sale price.  Redfin states last list price was $72K.  

I asked why and the response was, "As we talked about, Zillow has algorithms that take into account not only "normal" sales, but short sales, bank owned properties, and foreclosures. They are also not taking into account the $51K I'm putting into ("property A")... What these online firms are doing is looking at a property "right now" not once I've put all the money into the property.  This is why I will include an appraisal range with every property. Because of the volatility in the investment market, it's kind of impossible to say what value an appraiser, or a Zillow, will give a property."  The lowest appraisal expected is $120K per this turnkey company.

The explanation makes sense I guess.  $72K+$51K = $123K..  $20K difference vs selling price to me for the overhead I suppose?  The turnkey company emphasizes that they don't simply do lipstick on a pig which I think is great.  Although I am still wondering if purchase price (taking into account rehab) should be close or below comparable values in neighborhood?   I think what it is is that I watch a show like Flip or Flip here the couple will buy a distressed property , perform the rehab but sell it at or slightly above market value but it is still within market value.   So I still can't help but feel like the asking price is too much?  Am I missing something still?

Also another question. As you build your portfolio, is it common to establish an LLC .. in case a tenant sues you or other liabilities?