I own an SQ-A and an SQA-M (motorized). I think the SQ-A is a good deal, since it is newer than the plain vanilla SQ. Look for an SQ-A someplace besides the big five web sites, where you will pay absolutely top dollar for used medium format. Buy a copy of Shutterbug magazine, and call or e-mail some of the *smaller* companies in the secondary markets in the USA if you need a good deal.
It's possible to buy an SQ-A w. waist level finder, a 50mm and 80mm, with a 120 back for as little as $300 for the pair, with a motivated seller: I know, since I payed that little in 2008 for the exact listed stuff in Mint - shape. The 150mm PS lens is a nice one to have, and consider that you can also get a 645 back for the SQ series bodies to give your lenses a bit of added flexibility.
e-Bay is another place to get good deals; the biggest web site in the USA have prices 30-60 percent higher than you'll find from motivated sellers.