Solidworks can open and import quite a variety of file formats. For the most part, if a part is designed in one program, say Solidedge or Pro-E and then imported into Solidworks you may very well lose the design structure (not true in all cases). In most cases natives are transformed to a generic solid model in the form of a step or iges file which is easy to open in multiple packages. But again it'll be a form with no design information as to how it was built.
Most CAD development companies have tiers of software. Take Dassault Systems for example. Solidworks would be their mid-tier software whereas Catia is their top of the line powerhouse.
Last time I purchased a copy of Solidworks it was in the neighborhood of $7500 per seat w/ 1 year service (free upgrades, patches, phone support, etc) Add on packages such as COSMOS Works I believe tacked on another $5K per seat.
For the record, the reason I use Solidworks is not because it is "better" than Pro-E (Pro-E rocks IMO) but because 90% of my customers and vendors use Solidworks for their design software so it is very convenient for us to communicate design information.