Yes, lenses that work on the Maxxum (a.k.a., Dynax) 3000i will also work on a KM or Sony dSLR model.
The value of the 70-210mm would depend on which one. The Beercan (70-210mm f/4) is the most desirable. The lenses 70-210mm lenses that are down to f/5.6 on their long end (70-210mm f/4.5.-5.6) are not worth much and are best avoided on a dSLR for good quality.
The 50mm is probably a 50mm f/1.4 or f/1.7 (unless it's a 50mm f/2.8 Macro). These are all good (any even the cheaper f/1.7 is probably worth close to what the package price is if it's in great shape).
To get a better feel for what a vendor is selling these types of lenses for, go to http://www.keh.com
and look at the Camera Store under 35mm (not digital), Minolta Autofocus and you'll see choices for zoom lenses, etc. They usually have these lenses in stock.