RE: Single shot .223
I have two H&R single shots. A .223 & .22-.250 both shoot well. I would recommend a good scope also. I have a Bushnell 3200 elite mounted on both. Both guns fully equipt ran me less then $525 each. You can also get a Savage with the Accu-trigger for around $500 without anything added. I have two of these in .243 and .300wsm both are tack drivers with Leopold Vari-X scopes in 3x9. Perfect for deer and any biggame.
Back to the subject, get a single if that is all you can afford. It's a great rifle for varmints. I have the Flute Varmint with bull barrel and adjustable stock. I feel Like Carlos Hathcock the sniper when I shoot that little gun.