Wait a little bit longer for an additional $100, then go get a nice Ruger Single Six for about $350, or even a Taurus Model 94 for about $300-$325. If you find a S&W K-22 for under $500, buy it. The H&R noted by others above is also a good choice.
Avoid Charter Arms and Rossi, Sauer & Sons, etc. They're just not built to last a lifetime, in my opinion.
Don't want to tell you how to spend your money, but a good .22 revolver is something you only need to buy once in your lifetime. Spend the money and get a good, quality piece and you will never regret it.
Figure the cost this way : Forty years at $350 is $8.75 per year. Your $300 bargain is $7.50 a year. For a buck-twenty-five, there is no reason to spend the money two or three times and run yourself up to $750 or $1000 for finally getting the good piece you wanted to get in the first place.