Are your old SLR camera lenses Pentax or Ricoh compatible? So far all Pentax digital SLR's can use older PK/A manual focus and autofocus lenses made from 1985 to today. They can also use older P/K lenses and screw mount lenses from the 1970's, but you have to set the aperture manually. Today's SLR lens prices can start at about half the cost of the camera. The old PK/A lenses now sell for 10 to 30 cents on the dollar compared to their new prices back in their day. $20 to $50 buys most non-professional autofocus PK/A lens.
Pentax digital cameras are not full frame yet, so they only use the best center 2/3's of the old lenses. The down side is the old lenses act like their focal lenght is 50% longer on a digital camera compared to on a full frame 35mm SLR, i.e. a 28mm lens acts like a 42mm lens on a digital camera, a 100mm acts like a 150mm and a 200mm acts like a 300mm. Older lenses are heavy by todays standards, but they are also better quality than todays kit lenses. You can experiment with some very good quality older lenses for very little money.
You can also install an old-style split-image focus screen in a digital SLR if you like to use manual focus lenses often.
I have not been happy with the picture quality from a newer pocket digital camera. On paper 12 megapixels resolution should be outstanding, but the new plastic lens falls short of the glass lens on a 10 years older 3 megapixel camera.