How about something like "Generous, competitive salary"? Would that work?

Heh, it's definitely a tricky one to spell out, agreed :)

If it was me, I'd go with a more personal touch, something along the lines of: "I know that good developers don't come cheap, and I'm happy to pay market rates for the right person."

Only thing missing is whether you're talking about permanent employee rates, or consultant rates, but it addresses the biggest of my concerns.