First, if you can't afford an UX guy, even just paying him something fair, then why even hire one? Work with him as contractor first but for a fix rate rate. That way he doesn't have to leave his paying job and gets to work with the team. Nights or weekends whatever works for him.
Second, again you probably don't need an UX guy now. Dig into your heart, whats not working for Minutebox? User adoption or just the plain old people are just not finding it. If that's is the problem, then you won't turn it around by hiring a great UX guy. You only need the UX guy when you get tons of users and you need someone to make the experience of using minutebox better for them.