Prior to the 1990's, Ralph was cheap. But since then, his coaching hires have had NOTHING to do with cheapness. He had Marv and IIRC, Marv wasn't underpaid. Then he hired Phillips, who was the Bills' DC, and it's not uncommon to promote from within, right? Then Williams was a hot head coaching prospect, was he not? And Mularkey was more of a sell-job by TD IMHO, and the other top candidates were interested in other jobs.
And the point about the discrepancy WRT paying players but not paying coaches is a great one.