Soesman,
Good observation. Yes, this is a problem I haven't solved yet, or, at least my solution is not very elegant.
It is my perception that it is harder to daytrade a low priced stock, because just noise of the market tends to create trouble with your stops if they are too close. I find it easier to daytrade higher priced stocks, but maybe it's just me. And, although this journal here is basically about swing trading, I do tend to daytrade the positions a fair amount.
The way I handle this problem is to try and buy/sell fewer lower priced shares than a straight pecentage would dictate. In this way, I keep risk pretty close to the same "per trade." But, I do look at the chart and make sure I want to play that particular low-priced stock under these conditions. Make sense?