I'm still in the black by a good margin but I don't want to maintain the property all winter and there's no sure thing of selling in spring.On the other hand, my Greenlake rental flew.  

Certainly the margins are decreasing due to both increased government regulation and market saturation.But professionals like Neil Collins here in Portland, who self-manage effectively, and can deal with government wonkage effectively still have profitable margins.  

Whatever you buy, do it with a margin of safety (reasonable discount to market value) to ensure that you can weather some storms.

If you ask too much, and gain that reputation, the market will tell you very bluntly and you will be associated with all the other wholesalers that are pushing properties with very little margin.

Looks like your typical marginal deal to me . 

Brokerages have to issue margin calls (Federal Reserve rule) when the value of the stocks declines.

Moving these a few percent especially for larger purchases affect margins by quite a bit.

If the cost of management ruins the deal then the margins may be too tight and it probably isn't that good of a deal.

The margin 25-30% can be even smaller. 

Good profit margin