Or IRS?

Nothing beats being able to hop in your car, take a short drive and put 'eyeballs' on your investment.  

Recognizing the huge increase in home-based offices and businesses, the IRS even simplified the deduction in 2015 to allow more at home workers to claim it.

Am I using the price as if Id purhased new or do I have to use some generic comp number that the IRS has oayed for suh situations?

Here is what the following IRS link specifically lists. https://www.irs.gov/retirement-plans/plan-sponsor/...IRS Language“Trusts and trustees. 401(k) plans are funded through a trust established to hold and invest the plan’s assets.

Also sales tax part can get IRS interested. 

(Note: an S Corp is not an entity per se but an election to be treated differently by the IRS). 

Be sure to hop in on discussions and ask questions, that's the best way to learn more and meet other local people in the industry.

With that said, why take the risk of losing a case when all you have to do it simply get a business tax ID number from the IRS (for free) and setup a business account. 

. ;-)Anyway, why don't you take a look at Schedule E (to from 1040) to derive at the answer to your questions: https://www.irs.gov/pub/irs-pdf/f1040se.pdfStarting with line 3 you will see all the relevant parts that are to be considered when figuring out your taxable income (emphasis on "taxable" as this is ultimately what counts with respect to this particular discussion here).The form is fairly straight forward IMO.