If you already know the stock's ticker symbol, Google's main search window is probably the quickest way to get a quote. Just enter the symbol. That's it! If you go to their Google Finance search window, you can enter the ticker or the name of the company. This is an improvement over Yahoo!Finance, which also provides quotes, but isn't as forgiving if you don't know the ticker symbol -- you have to manually look up the symbol first. Both Google Finance and Yahoo! Finance are portals to a wealth of company information -- charts, news, executive bios, compensation, etc.
When trying to place a value on stock for development research purposes, it's recommended that you use the market close price (yesterday's if the market is still open, or today's if the market has closed). That's because the current price is fleeting and volatile. It can change wildly during the day. But the closing price is recorded and commonly accepted for reference purposes.