The amount I put in is relative to the risk. I play mostly POS sub pennies - either a 30% loss or a 100% gain. Those I thro 2-5k into. I get into .10 - .50 - $5k to $10k depending on the nature of the trade.
Big caps - $20k - I went a month one time trading Nortel only or about 90% of my trades - I was trading a $40k float all day long
for me it totally depends on stock...the subbers - i'm not as daring as andy..and yet usxp was easy to buy 10-30k worth and flip all day long cause of the volume...but like dphie, xsnx, ptsc, cwpc etc etc...no problem puting in 50-150k worth when it feels right..especially on bounces...
it's all about float and volume and feel of stock...