At one point in their history, Minolta was the largest camera company in the world thanks to its innovative technology such as auto-focus integrated into a camera body. Konica Minolta still exists today but they don't make cameras or lenses any more after passing the beacon onto Sony.
Luckily for many strong Minolta SLR fans and enthusiasts, Sony took over digital imaging production from Minolta and many workers from Minolta now work at Sony. The best part about the decision to take over Minolta's imaging business is the lenses. G lenses Even people who didn't use Minolta cameras envied the quality of the G lens. Amazingly, Sony have kept the quality of the Minolta G series and released the Sony G series. For the DSLRs, they've also kept the old Minolta A series auto-focus bayonet mount, which means that any Sony DSLR can not only fit new Sony camera lenses to it, but also can also accomodate older Minolta camera lenses. This backwards compatibility is great for users of old Minolta cameras because they can fit new lenses onto old cameras, including the range from Sony's alliance with legendary lens maker Carl Zeiss.
Minolta lenses can't be bought new although many websites list their third party products as Minolta to get traffic to their site. However, the A mount lenses from Sony and Sony fit third parties such as Sigma and Tamron are compliant with older Minolta cameras such as the Minolta Dynax 5, Minolta Dynax 7 or Minolta Dynax 9. These lenses are available from any online retailer such as Warehouse Express, Cameras2u, Ebuyer and Amazon. They're also available in stores on the High Street such as Jessops, Park Cameras and any independent outlets in the local area.
There are Minolta lenses available second-hand, usually in the same places as the newer A mount lenses for Sony. However, high Street stores are less inclined to sell second-hand stocks because of the downturn in interest from the consumer. The popularity of websites such as Ebay make it easier for the consumer to get a second-hand lens such as the Minolta 85mm f/1.4 AF G. It is still an excellent lens and a model in good condition can command up to £600.
As with anything, look around for the best deal and try the models out in a shop first. Do some research into the best quality using reputable sources such as Minolta forums and photography websites such as PhotographyBLOG, Steve's Digicams or Talk photography. These provide the best impartial advice when looking to buy a Minolta lens for your digital SLR camera.