Cooper/Black - Terry gave you the links for the H/D GoreTex Pac Lite Rain Gear already. It's what I am using & it works well in warm weather since it is not lined & it wicks perspiration away. For cold weather, make sure you get rain gear that is big enough to go over a jacket since the pac lite stuff is not warm enough to wear by itself in 50 degree rain. Pac Lite compresses into a reasonably small area - some of the other Gore Tex stuff is kinda bulky. I prefer lighter weight & then layer up as needed. The H/D version has some reflective material on the outside. Other Pac Lite is available (non HD) & you may find some deals on it. That Sierra Trading Post (also linked above)is a GREAT company. Had the pleasure of visiting them in person on our bike trip to Cody, WY a while ago.
BTW - TCnBham is one of the very best sources for info on this board - or anywhere for that matter on motorcycle stuff.
Years ago when I was broke, a regular black trash bag with a couple of arm holes ripped in it was my rain gear. Did not do much for arms/legs & it leaked of course but in a pinch, its better than nothing. Now I'm broke from buying all this spiffy gear, but I'm more comfortable, dammit. 
D00d - I considered FXRG gear & have not ruled it out for a future purchase. Watching H/D's revisions on it to see if it gets closer to what I am looking for.
Mike, you make me blush, buddy...

There's so much I don't know about motorcycles it scares me, but I am a gearhead on this kind of stuff.
I too have used plastic bags for boot liners, ponchos, etc...they are absolutely no fun, but when you're eating oatmeal and peanut butter, with the occasional 33 cent Taco Hell Burrito thrown in, you do what you've got to do. Army surplus was my beginning "outdoor gear".

When you are 20 something you don't seem to notice being miserable as much as when you're 50 something.
The Frog Toggs will work, and they are cheap...they will melt in a New York minute though, and I'd just as soon not clean the stuff off my pipes. Most of the better stuff will not melt very easily, and some even have a different material on the inside bottom of legs for extra durability.
The one advantage of the skiing/backpacking shell type jackets is they are normally made to put other things under them. The HD gear is not cut large enough to wear a heavy leather jacket under, so that's where the other stuff, like fleece, comes in. Fleece is the best thing for keeping warm since pajamas with feet in them...great insulator, will not absorb water (it's plastic), and it wicks the moisture from your body to the surface of the garment, where it evaporates quickly.