Hi olivebugger,
You are at the lower end of fly fishing rain jackets. I think your best bet may be the Cabela's GoreTex Jacket. It is in your price range. If you want to go up another $50 then Orvis sells their Tailwaters NO Sweat jacket. It is not GorTex but Joni likes them. You should also look at the Columbia Queets River jacket. It is not GorTex but I have read good reports about it from those who have bought it. It is also available from Cabela's and will save you $50. Right at your budget is LL Bean's Stowaway jacket. It is GorTex. Last but not least is the Simm's Freestone jacket for $20 more than your budget. This is a good jacket but is not GorTex.
Frank
Cabela's Gore Tex Jacket
Columbia Queets River Jacket
Simms Freestone Jacket
