Kenmore Reverse Osmosis Drinking Water System #625.347001 Push in Fitting

[propguy]

I need to replace a 1/4" and a 3/8" Push In Fitting that are leaking. These are fittings used to connect the PEX tubing to the RO unit. Sears Parts wants $8.99 each for these tiny plastic pieces plus $9.00 shipping! The Sears part #'s are: 7209566 and 7209574. Does anybody know where I could obtain these parts besides Sears? I could not find who manufactured the RO system.
I don't mind paying a fair price but $8.99 each plus $9.00 shipping for maybe 2 ounces seems a bit steep!   

[JWWebster]

You have an ace hardware store near you?
http://www.acehardwareoutlet.com/ProductList.aspx?CommodityGroupId=40&MerchandiseClassId=490%20&ProductGroupId=2

[propguy]

Thanks for the reply JW. To be more specific the parts that I need are the end pieces or ferrules.  The ferrules include a small O-ring also. These ferrules are pushed into the housing, then the tubing is inserted. They allow the PEX tubing to be removed when you push down on the ferrule. I have checked Home Depot and Lowes. They have a large selection of push in connectors but not what I'm looking for. I don't have an Ace Hardware close, but looking at their stock it looks the same as Home Depot, etc.