How big of lots would you recommend trading with. I currently have approx. 10k in my ameritrade account that I trade. I have oscillated between $1k purchases and $5k purchases. For the $1k I have to make a good like to pay for the trading cost. For the $5k I get really really nervous as half my kitty is tied up. Any suggestions from you guys on how much I should invest on stocks to stay balanced.