since you may be by yourself on the day of the garage sale, I recommend listing your garagesale on craigslist.org in the ad, you can state that you have the refridgerator for sale and to call if they want to come by before the sale to check it out. Also list the fridge under the household section as well. I had a garage sale 2 weeks ago & did great on sales even before the day of my sale because I listed my ph# for people to call & come over before the sale. During the sale, if you are able to get someone to be there with you, keep mentioning that you have the fridge for sale when you have groups of people there, also put up a sign stating you have it for sale & tape it to a table or maybe make a big poster & hang it from the garage.
ITA that expecting $400 is not likely. Even though it may be fancier than just the basic fridge, it is 10 years old, out of warranty & probably not very contemporary looking as the styles seem to change from time to time. I personally would be afraid of shelling out $400 and 6 months later it clunks out. Right now you can get a brand new 25.1ct ft side by side water/ice dispensor on door Kennmore for $750 and several others from Sears for less than $1000.
You can typically figure selling used items for about 10-25% of what you actually paid for the item, especially if the item is 10 years old. That being said, I'm still trying to sell my 6 yr old big screen tv for the past 3 weeks with no takers. People are just afraid of shelling out several hundred dollars with no guarantee that what they buy will still work in a couple months.