I have this one and its perfect.

Amazon.com: Samsung CAD300UBEB/STD Standard Car Power Charger: Cell Phones & Accessories

 

I buy the Griffin Jolt power chargers. The one for my iPad is great because it has a slightly higher watt that chargers quicker. I did't see one for the SF but any micro USB should be fine. I ordered the Droid X charger. micro usb is universal.

Griffin Technology: Solutions for Motorola X

 

I bought this Motorola one for my SF and it is excellent, perfect for me. It glows blue when charging the phone and I love the effect too. Very cool. Also its output is 950mA and that equates to very rapid charging. If you buy this, make sure you get it from Amazon and not any of the other sellers on the site.

Amazon.com: Motorola Vehicle Power Adapter micro-USB Rapid Rate Charger: Cell Phones & Accessories

 

I got this in September for my SF Amazon.com: GTMax Rapid Car Charger with IC chip + Home Travel Wall Charger + USB 2.0 to Micro-USB Cable for Verizon Samsung Fascinate Galaxy S CDMA Cellphone: Cell Phones & Accessories
Its less than $5 delivered now. Reviews don't look so hot but again all I can say is this is exactly what I have. I rarely use the car charger and the wall charger is about a foot shorter than the stock one. But I use the usb cable all the time and all in all getting 3 cords for less than $2 each isnt bad.

 

For the one I posted earlier, I'm showing $4.00 and free shipping for the one on amazon. I bought this and guarentee its made by samsung. (Look on the right hand side for more buying options - OEM Shop) Thats not a good deal?

Also you want to make sure it has the low profile connecter which this one does. Generic ones have a bigger connector that tend to fall out of the phone. Not saying that these EBay ones do but its hard to tell.

Me personally, i would never buy anything off of eBay for my phone that involves power. Its a $500+ phone and not sure i would trust a 99 cent charger. It says OEM but you never know, there is no guarentee.

Just my 2 cents.

 

Look on the right hand side where it says 'More Buying Choices'. The one for OEM Shop is where i bought mine from.