Unfortunately, less expensive alternatives are going to be hard to bootstrap: a new, no-name journal almost by definition hasn't had the chance to establish prestige by publishing papers which go on to get widely cited.
Well, it depends. If (and I admit that this is a huge if) you can get a couple of really big names to start publishing stuff in your new journal, you can bootstrap a journal pretty quickly. However, for this to happen, the big names that you're dealing have to be really, really disgusted with their current journal.
Not just with their current journal (the big shots usually have a choice of venues), but with academic publishing in general. But of course, what makes someone a "big name" in academia is that they've succeeded well in the system as it is, and aren't likely to be deeply aggrieved with it.
Well, it depends. If (and I admit that this is a huge if) you can get a couple of really big names to start publishing stuff in your new journal, you can bootstrap a journal pretty quickly. However, for this to happen, the big names that you're dealing have to be really, really disgusted with their current journal.