most 'long term investors' fail not because their broker charge them $10/month.... they fail because when the market is going up they all think they can be there for the 'long haul', but the moment the market drops, they can't sleep, can't take the pain, have to sell at the bottom so the pain can go away.
ask yourself, how much draw down can you handle without losing sleep? if it's $10k, then that means you can only buy $20k of stocks, even if you have $500k in hand.... you have to put the other $480k in bank CD... that's what I meant.