Hi Gary,
Your best bang for the buck in my opinion is for a circulated Liberty $5 gold piece. They contain 0.2419 ounces of pure gold. You should easily be able to get a nice one for well below $250. I bought an 1881 coin from Long Island Rare Coins recently for $225; it was a relatively scarce repunched date variety and was certified AU53 by ANACS. You should be able to get a decent raw example of a common date for even less.
A US gold dollar is a nice coin, but it only contains 0.04837 ounces of gold and will probably cost almost as much as a Liberty $5 coin. If your primary goal is to accumulate some gold, the $5 gold piece is clearly the better choice.
I would absolutely stay away from those little fantasy pieces. Even if they are gold, you have no assurance of purity or total gold content and will consequently have trouble even getting bullion value for them if you try to sell.
Good luck!