Do yourself a favor and buy a good paddle..ASAP...I'm sure I'm not the only one who thinks it's such a big deal.
I used to get a lot of shoulder pain and it even sometimes kept me awake at night..I thought that I was just going at it too hard..and for too long..(paddling)

I thought it's something that will go away..eventually..but it never did (about two years of paddling almost every day).
Then after trying the carbon Naish, GSI, Starboard, South Point carbon and the C4 and Werner I bought my KIALOA paddle from SHQ..I guess it was a bit of a gamble.
I'd heard rave reviews from those who use them..These are guys that do the Hawaiian island crossings (about 30 miles).
I had also heard that the Kialoa is one of the lightest, thinest and flexiest shafts..Yet when I first used it it felt pretty stiff..but it has a springy..lively feel.
Since getting my new Kialoa paddle I've had no shoulder pain at all...So I'm a happy chappy..

..I even went back and bought a second I liked it that much.
Note that almost any good carbon paddle might have fixed my shoulder pain because before it I used stiff and heavy home made alloy paddles.
These cheap alloy paddles are great for getting you on the water in the begining..and for those who can't afford carbon.
One more thing that I like about the Kialoa is that it has a very ovalized/rectangular shape near the center of the shaft then goes round towards each end.
Naish have an interesting paddle coming that is more aimed at surf use..It's shorter and wider in the blade shape..It's also a dovetail or V shaped design.
Kialoa also have a new paddle coming (press release next month) that's a little smaller that the Shaka Pu'u..It also looks very interesting.
Then there's Werner...Werner are renowned for being the best paddle makers in the world..but mostly to do with canoes and kayaks.
There's heaps out there now and it's amazing how different they all feel...and it's about the 'feel'.

DJ