Got quoted about $90 for full main panel from a repairer in Sydney, which also ended up being recommended to me by several people/sponsors on this site.
$90 seems to be the norm', must be a standardized price.
I paid $60 for a panel on an Ezzy (uv damage) 18 months ago in peak season. The local windsurf shop said "They saw you coming". I think it depends on the degree of difficulty but a simple panel replacement shouldn't cost $90 IMHO.
yer i would have said $80 to $100, there is alot of messing around removing the torn panel, undoing all the stitching, making the new panel or panels exactly the right shape then glueing and stitching it back together. plus the price of a square meter or so of sail cloth, i know i would rather pay someone else to do it. And cheaper than buying a new one..