Welcome to Ub.c
First, a minor correction . . . that's an E30, not an E36; convertible E30's were produced up till '93 (I believe), although the E36 began production with MY '92. I don't know about the validity of it being an M-Technic; just because it has the body kit doesn't mean it is a geniune M. Maybe someone more knowledgeable here can answer that better. But an added body kit or any accessories should really not factor into the value of a car. For example, just because you slapped on $3000 wheels doesn't mean you can tack that onto the selling price.
And the steering rack & pinion itself should run you about $300. Then figure an extra hundred or so for other stuff, like tools you might need for the tie rods. If you want to save money, installing it is not too difficult, if you're willing to take your time with it.
As far as the Civic, you can't really fault it for a great all around, get around practical car. It's no BMW, but they're popular for a reason. Your choice