Many of the solutions you have to deliver to get substantial discounts on property would have to be solutions to headaches that nobody else (including the seller) wants to tangle with.If you can't find any compelling problem in this section, you should seriously consider moving on with your life by referring them to some sort of service provider that might be more appropriate for them.

Should the purchase offer be discounted by that spread? 

You'll want to feel reasonably confident you can hit closer to 2.75 to 3.00 times the rental rate to have a decent margin to compensate yourself at all for your time and effort.As others mentioned, your biggest risk with arbitrage is that you will not be able to cover your cost due to competition or due to regulatory conditions. 

We are making very good margins.

If they have a disposition list of buyers that buy discounted on market properties, then they will make offers.   

(counter offered me at 228k been on market for over 120 days) What are some tips to go back to the seller of the first one a request such a large discount.

If you need help with mailing ideas or want a discount on mailers please let me know!

with hotels you can opt to pay a little bit of a discounted price and its non refundable  no matter what or you can pay a tad more ( which is what I do) and you can cancel within 24 hours full refund.. 

For instance, log cabins and split levels sell at a discount in our area compared to capes and colonials. 

Mobile homes are very easy to repair; however, there has to be a large enough margin or a good exit strategy to cash out (if in a park).