They are in pretty good shape...excellent restoration canidates. They aren't Wonderboys...Wonderboys frist showed in the '59 catalog, but were made into 1960, as most documented examples with an original engine have a 1960 Briggs model 19 in them. At some point they simply changed the badges to drop the Wonderboy designation...it was confusing to folks used to the rear engine Wonderboys from years prior.
A 700 is a desirable machine...far less common than the hundreds of thousands of model 725's that followed them. I'd say they are easily $100 machines...in WI the guys may pay upwards of $150. Definitely don't want them sitting out any longer than you have to.