Summer riding jackets?

Even though it's cool by Central Florida standards (53F) today...I know that the hot, humid dog days of summer are not that far off.

So I'm looking for a new "summer" jacket. In the past I would either go sans jacket or open it up all the way. Now after my in December I'm not going without some sort of protection.

My black Vulcan jacket has served me well but frankly it's to hot. So what I hope to find is something lighter, yellow or hi-vis which offers me protection but will still provide enough air flow to keep me cool. I would rather it be rainproof as well.

I turn to you, my fellow rounders, for advice. I am a poor man and would like to keep the jacket under $150 if possible. Actually I like to keep it under $100 but lets be honest...that's not likely.

So...recommendations?

If it helps I'm about 6 foot tall (1.83 m) and between 200 - 210 pounds (90.7 to 95.3 Kilo). In either system I believe this is called "fat."