I use a plain old dial scale. I'm trying not to get too caught up in the fluctuations of less than 1 lbs so a dial scale works well as it doesn't give me a number to a decimal point. Each line is 2 lbs so when it's shifted I know I have something to be excited about! But, I know it wouldn't work for everyone. It's the cheapest one at wal-mart and was about $15.
for each 5 Pounds Lost - 
