The solution to both is investing in stock index funds and ETFs. While mutual funds might require a $1,000 minimum or more, index fund minimums tend to be lower (and ETFs are purchased for a share price that could be lower still). Two brokers, Fidelity and Charles Schwab, offer index funds with no minimum at all. Index funds also cure the diversification issue because they hold many different stocks within a single fund.
Overall commission costs can also be affected by new customer promotions. Brokers may give you a chunk of free trades based on your deposit amount. If your deposit gets you a substantial number of free trades, that can write off otherwise higher per-commission costs. Ally Invest offers small incentives for deposits as low as $500. Fidelity Investments, meanwhile, has a higher barrier for entry — it takes a $50,000 deposit, but then you'll get 300 free trades.
That said, learning the logistics of how to buy stocks and earmarking a small sliver of your investable assets to buying individual stocks online can be fun and profitable. And at worst? As long as you don’t put money you can’t afford to lose on the line, stock trading will be a temporary diversion that leads to limited losses, lessons learned and a few self-deprecating stories to entertain dinner guests.