If you want a book which is priced under $30, write it yourself and put it on the internet: then it's free.

(This is not a quip or a dismissive comment: please do actually do this.  I have done this sort of thing myself.)

Among books that the evil empires of publishing put out, I used one for such a course twice and -- apart from the price -- it was pretty good:

http://www.pearsonhighered.com/educator/product/Mathematical-Proofs-A-Transition-to-Advanced-Mathematics/9780321390530.page

I'm not sure exactly why you are against historical comments (nor do I know exactly what "mathematical perspectives" means in this pejorative context), but so far as I recall this book is fairly businesslike.  (<b>Added</b>: I just processed the part of your question where you mention supplementing the book with material from Courant and Robbins.  That latter book is all about perspective, so I guess the idea is that you want to avoid 
duplication of content, which is very reasonable.  Sorry if I sounded overly critical before.)

I was most pleased with the treatment of logic and sets in the first two chapters: just about the right amount, with just about the right level of formality and sophistication...to my taste, of course.