Christians..Heathens...hear me. In my opinion the OP was not real far out asking for advice here. More than likely he knew (or suspected) he might get a roasting, but was willing to risk it in order to achieve something. Ok.
Most sign guys (and gals) are supremely sensitive to this very kind of thing. That their particular shop or even a brother-in-the-trade's shop might get knocked "out of the loop" for some church banners irritates them. All this is based on the "principle of the thing" of course.
But let's not be overly critical, or may I even suggest it(?), hypocritical.
How many of us own auto type tools so we don't have to use a local mechanic? Or paintbrushes to paint our own homes and further screw the local painter's union? Point is, we all act in our own self-interest. The OP wants to save the Church money that would otherwise be spent on banners to, presumably, help the poor, aid the sick, etc. Church stuff.
The fact that he came here can be viewed by some, as an affront. Ok, to them it certainly is, I won't argue that. Our feelings are our feelings. To others, myself included, no big deal. He took a chance, took a beating for it, and heck...I'm none the worse for wear. Some here even offered some assistance and figures to help him weigh the pros and cons.
Such is life. This isn't some dress rehearsal. In the big scheme of things, it won't matter tomorrow.