that lets you buy shares on installment and without imposing margin rules. As you know, those retail houses like E*trade, Ameritrade, TD Waterhouse, Scott trade,... impose margin rules on your account like $25K limit, and if stock market drops to certain level, one can't maintain the margin, then they will close your position, consequentially, you lost a chunk of nestegg ... Yes, I have a long term horizon
So I'm looking for a company" that lets you buy share(s) of stock on installment like $1000 a month, some sort of dollar-cost average scheme. This way my money will be safe regardless of how the market is. if market drops, they won't exercise margin call.
Many brokers will let you buy baskets of stocks for a round number like, as you said, $1000. You should check if the broker charges you full commission on each individual stock in the basket... that could add up to a lot with some brokers.
There's no $25K margin rule that I know of... there's a limit on daytrading if you have an account that's less than $25K, but from your description it sounds like you won't do daytrading.
Every broker will enforce margin rules, though, partly due to Federal Reserve rules and partly because they're loaning you money and need to protect it. If you don't want to buy on margin, you can open a cash account; you won't be borrowing the broker's money, and you won't have to worry about the broker liquidating your account due to a market downturn.