I think it runs much deeper than that - sure, there are some well documented chemical feedback mechanisms - sugar enhancing appetite, fat making you feel full, etc - but I think there is a more fundamental issue, food has become too convenient.

Food should not be convenient, it reduces the psychological value of the food. This is a difficult thing to explain, try this as a simple test:
Buy a bag of frozen peas (I think frozen peas are really good for you as a food item, this test is all about convenience)
Set out what you think is a reasonable portion for you, weigh the portion, then cook them simply.
I tend to steam them over some boiling water, then add a little salt, pepper and butter before serving.

Now try buying some fresh peas, still in their pods from your grocer (supermarkets rarely carry them)
Sit down and shell the peas into a bowl by hand, until you think you have a reasonable portion. Don't throw away the pods, they can be used to make a soup.
Weigh the peas and then cook the peas the same way as you did before.

You should discover two things:-
1. That there may not be any difference in the portion sizes - chances are you will make more effort to accurately judge the amount you require if there is more work involved.
2. You should feel satisfied more quickly when you eat the second dish, and probably feel the need to eat less of them as a result.

Scientifically there is nothing to choose between the two plates of food - frozen peas are arguably more nutritious than all but the freshest of fresh peas. The only difference is in your head.

One of the key things with lap banding, is that it makes all food less convenient - you can work around it by 'grazing' on lots of small meals, or by doing stupid things like blending mars bars - but it is a lot, less convenient than it was before.
But you do need to ask yourself if the right way to deal with the modern diet is to artificially cripple yourself.

Hoobley - it's much harder in the UK as the supermarkets do have much more of a strangle-hold on the food supply and have discovered that if they process and package everything then they massively increase their margins - so they actively make it difficult for you to buy unprocessed food from them by charging a huge premium for it.
You might want to investigate other sources of produce - most councils still have allotment schemes running, even if you can't spare the time to grow your own, there is often surplus produce that cannot legally be sold - many growers are happy to give it away if you make it easy for them. It's also well worth finding out about local farmer's markets when you can buy directly from the growers - nobody wants to take unsold food home with them at the end of the day, so go at the end of the market and haggle...it will be better and cheaper than the supermarket.