The situation hasn't progressed very much in 30 years, kitty.
Certain colours will command higher prices. I dare say the petshop owner you overheard knew he could get £80/£100 for gingers. People will pay a premuim for gingers, and also pure white or tabbies. Sadly paying a premium doesn't guarentee a good home, all it guarentees is an owner more interested in colour schemes. The petshop will probably only offer a tenner for black/black and whites as everywhere is awash with them.
Although some good owners do/have got their cats from petshops and will take very good care of them, a high proportion won't actually bother with neutering or leave it too late and hey-presto.. another accidental litter!
The biggest problem is that kittens seem to all come at once. As soon as the weather improves in Spring, entire queens will come into season within a few weeks of each other. Those first litters will be lucky and get homes easily... then the floodgates open and supply vastly exceeds demand. From there on it snowballs... Give it to June/July and the free ads will be awash with free-to-a-good-home listings. If those kittens are lucky they end up with rescues who will get them properly health checked and vaccinated and they new owners will be made to neuter them when old enough. But rescues only have so much space and sadly even we have had to turn kittens away this year.
Kitten season started very late this year so everything was delayed and there are some Autumn kittens still waiting in rescues for a new home, so inevitably there will be BSBs litters out there being sold this Christmas to irresponsible people. I will be on emergency stand-by over the Christmas period for dumped unwanted Christmas present kittens. They'll be a nice, clean and warm kitten pen plus bedding and food at the ready in my bathroom. We are hoping for a quiet time but we never take anything for granted.
Over the last 3 years I've taken in and fostered over 250 unwanted and dumped kittens at all times of the year. And that's just one volunteer from one rescue. So what does that tell you? Many, many people still aren't listening to the neutering message.