I bought an outer jacket from Voler last year for rain and it works great and it was only $13 which sold retail for $18, not sure why they quit selling it, I guess they wanted to raise the price $99 because the new one cost that much and looks almost the same except it has a zipper instead of velcro closing! Just go to Amazon and type in cycling rain jacket and chose the cheapest one with high ratings. I'll combine this with a breathable light jacket made by Garneau, or if colder then I put on a thicker jersey with the light jacket then the rain jacket to block the cold.
I also use a rain pant which I got cheap from Walmart but works very well against rain and cold wind and it was cheap.
If it's raining heavily I'll use shoe covers which all I got was the cheap Nashbar brand which works fine.
I also have a helmet cover which sort of looks like this one:
http://www.amazon.com/TAIGA-Helmet-Rain-Cover-Waterproof/dp/B00NUHHMUQ/ref=sr_1_15?ie=UTF8&qid=1448133090&sr=8-15&keywords=helmet+rain+cover I like the rear flap because it prevents water from draining down my neck and into the jacket but cheap ones like this work too as far as keeping your head from getting wet; see: http://www.amazon.com/Rockbros-Windproof-Dust-proof-Mountain-Helmet/dp/B00WSJJHC8/ref=sr_1_3?ie=UTF8&qid=1448133090&sr=8-3&keywords=helmet+rain+cover Also when it's cold and raining I'll had an internal head beanie.
I will also wear cheap clear safety glasses in the rain that have an aero look to it, they help to keep the cold air from blasting my eyes, I treat the glasses with RainX so the rain just flies off the lens leaving them clear.
Riding in the rain or on wet roads requires that you drop your psi by about 10 psi, also stay off of painted, including painted stripes, or steel, wood, or plastic surfaces as these will be very slick.
Use a light in the front and rear and set to flash mode.
Lastly you might want to consider fenders if you don't want crud flying up the back of your jacket and or want a cleaner bike when you're done. From everything that I've read I think these are the best; see:
http://www.amazon.com/CRUD-RoadRacer-MK2-Road-Fenders/dp/B00435NFKA/ref=sr_1_1?ie=UTF8&qid=1448133491&sr=8-1&keywords=crud+fender Some fenders have been known to get objects stuck on the tread then get jammed into the fender which resulted in bent or broken forks, while I never seen this or knew of anyone this happened to I have seen examples on the internet so I think it's rare, but it's not something I would ever want to see happen and the Crud fender will prevent that because it just moves away instead of the fork. I use a Planet Bike Cascade fender set on my touring bike but just a Planet Bike Flipper on my commuter bike; haven't decided if I want to buy the Crud fenders yet. There is also a Planet Bike Grunge board which mounts to the down tube to help the tube from getting overly dirty, I don't know about this, I don't use one I just wipe the bike down when I get home which I would have to do anyways..