I'm not familiar with Special Projects mics. A google search only came up with some headset mics for sports applications. Studio Projects is a reputable company, but I don't see where they are coming out with a ribbon mic. Do you have a link to the mic you are asking about?
I've never heard of them either. The ribbon mics sold by ShinyBox are getting good reviews, especially their model 46, which they sell their basic version for $150. I'm about to buy one of these myself.
That's the same mic as one of the ShinyBox & very similar to the Nady, etc. They all come out of the same factory in China and are re-branded. Personally, I'd go with one from a name I at least know just to get some sort of warranty and/or customer service. The Shiny Box mics are cheaper than that one, too.