Congrats!
Don't forget to include in your ROI calculation the opportunity cost of your time spent pursuing all prospects for that particular domain. For example, in my consulting business (unrelated to domaining) I charge anywhere from $150 to $250 per hour depending on the level of expertise I am providing to my clients. In my ROI calculations for domaining, I include the cost of my time in pursuing end users because there's a real opportunity cost there (i.e., I could be billing clients instead of domaining). To leave out the cost of your time is to be remiss. It's a real cost we should not ignore (ask any economics professor).
So, if you bill out at, say, $50 per hour in your normal line of work and you gained ownership of CheapFlutes.com for $47 and it took you three hours of your time ($150) to find suitable prospects, reach out to those prospects via emails, and then convert this one sale for $150, your ROI is actually negative. You may have been better off waiting for a better offer from a different end user or simply avoiding the purchase of that particular domain name in the first place because it never would have attracted a sale price that could adequately compensate you for your time spent trying to sell it.
Also, being a finance guy (I'm a CFA), I've seen a ton of people in all walks of life miscalculate their ROI%. Be sure to use this formula to get it right:
ROI% = 100 x [(Sale Price / Total Cost of Sales) - 1]
So, from my example above:
Sale Price = $150.00
Total Cost of Sales = $47.00 acquisition costs + $150.00 time selling = $197.00
ROI% = 100 x [($150 / $197) - 1] = -23.86%.
If this example is anywhere near your total cost of sales, selling for $150 was not a good deal for you. It was a great deal for the buyer though because he didn't even have to cover your costs of acquiring the domain name here on NamePros, making him aware the domain name existed, was for sale, negotiating the sale to a close, and transferring the domain to him.
