The best advice that I can give is to be patient. If you keep on looking, you will find what you want. I readily admit that I know nothing about the Heritage brand of revolvers. If that is all you can afford then by all means buy one and if for some reason it doesn't work out, you won't have a bunch invested in it.
However, if you look around long enough, sooner or later a good deal on a Single Six will probably show up.
Two years ago a fellow I know came to me wanting to sell a couple Ruger single action revolvers out of an estate where he was the executor of the will. I really didn't want them at the time, so I passed on the deal. Six months later he came to me again and offered me the same revolvers, only this time much cheaper as the widow was anxious to get all the firearms out of her house. The price was so good I just had to buy them.
One was a New Model Blackhawk in .357 and the other was a Single Six. The Blackhawk was in good condition but the .22 had been stored in a humid environment and had some rust. Picked them up for $225 + transfer fees for the pair.
I know, without pictures it didn't happen, so here they are:
The Single Six