I need your help guys.  My aluminum prop that is currently on my Mercury 9.9 HP 2 stroke motor has chipped thin blades becuase my fishing partner and I are pretty rough on it.  We fish a very shallow river and it frequently hits the sandy bottom which causes the blades to thin and then chip.  This prop did last about 4 years.

Is a stainless steel prop worth the extra money ($200 -vs- $100)?  Will it last longer than an aluminum prop in the above circumstances.  I also hit stumps with the blade occasionally.

For the conditions you have described , DO NOT get the stainless steel prop.

The stainless is far less forgiving when you hit something, and you will do damage to your lower unit instead[and you do NOT want that to happen, trust me].

No unless you go with Powetech's cushion lock system, but I don't think they make it for smaller props. 

9.9 HP props are pretty cheap and can be picked up for a song on Ebay or Craigslist.

You can get the aluminum prop rebuilt and the money you don't spend on a stainless prop can be used to purchase a prop guard.

Pretty sure you can get bushings for those so it strips before your lower unit takes the force.  I know my Turbo Prop has one for my 90hp.

And like Wayne said, you may look into a guard. I opted against one for my big motor because they do hinder performance. But if all your using is a 9.9 anyway, it may be worth looking into.

http://www.basspro.com/webapp/wcs/stores/servlet/Product_10151_-1_10001_20945_225011000_225000000_225011000_225-11-0

Put one on my Merc 25 and ran it really hard both duck hunting and fishing Toledo Bend, smaller creeks and rivers, and even saltwater marsh and it was the best money I ever spent on that boat. In fact, that motor and prop are on another hull, as I wore out the 15' .100 Welbuilt (bottom looked like you had attacked it with a sledge hammer), and it is still going strong after nearly 15 years. However, if you do get a stainless prop, buy the Merc prop; I bought the first one from Cabelas and it had too much cup in the blades and the motor was bogging down...sent it back and paid a little extra for the Merc prop.

Thanks guys.  I will check ebay, didn't think about that.  I tried a Macs River Runner last year but it took away from the performance too much (1/4) so I sold it.