If you don't care for other traits (which are usually useless) you can get them for less than a million EC on the Exchange.
You can get them from DOFF missions (Achievment X: Saurian X Bridge Officer for example).
Search for Rare or Very Rare quality, starting at a million and up from there. Borg Boffs get it as well, but to buy them you search in Reward Packs instead. And its not that they 'greatly' increase your abilities, its just that Efficient is the only Boff trait that enhances space combat at all, equivalent to something like an extra +10 or so in Starship Warp Core Efficiency, for an extra point or two of power in each of the four categories. Still, its a lot more useful than Superior Covert and other such junk.
Where do you recruit Saurian bridge officers from? I mean its hard to find Federation Boff recruitment missions in general. Its much easier on the Klingon side unless I'm supposed to go somewhere special in space?