Is it time to either create a minimum hash rate, or a minimum transaction amount?

There are some rigs on the site with such a low hashrate that even purchasing 7 days is less than a transaction fee - this seems absurd.

Who is even interested in 6khs hashrate?  I wonder if a more reasonable 300khs bottom limit is placed, and perhaps this is even too low.  Even a low grade single 270 card should top 400khs.

I notice alot of the lower end cpu miners have lower rating scores, and perhaps another way of dealing with this is to allow searching by only 10/10 rigs or those with a rating.