it sounds like he means 1% roi ($101 return on $100 invested) ... but that amount of money is irrelevant when compared to not wanting to saturate the market with more competition and raise the price on your own bids, doing this would truly be shooting yourself in the foot.
If you have the knowledge, $400 or even $1000 is less than a month of most campaigns running at full speed. Go find yourself a spammy
ebook and save that $400 for your 1st weeks worth of losses.