I will admit there is a societal trend to just relabel high meat low carb atkins type diets as paleo, and be done with it. That doesn't mean the paleo diet is "eat organic steaks every night".
As a programmer/hacker community the best analogy I can give is my impression of a venn diagram of a atkins/low carb type diet is the circle for the diet mostly contains meat and not much else. And the venn for a paleo diet also contains a small circle for meat, along with a whoppin big circle for fruit/veg/nuts. True both don't have grains/beans, and neither are vegetarian, but thats about it for similarity.
Another interesting analogy is the ideal stereotypical atkins low carb meal probably is a steak as per your example. The stereotypical paleo meal is probably a big ole salad full of veggies with a normal sized grilled chicken breast on top (not one of those mutant ones the size of your forearm).
Finally having fooled around with both diets a low carb ketone mode diet is super sensitive to what you eat; highly disciplined. Eat one apple and you've ruined days of work getting into ketone mode. On the other hand a paleo type diet has more to do with priorities and general trends. Always have more bags from the produce aisle in the cart than bags from the breakfast cereal aisle, that type of thing. I had a bowl of ice cream at a celebration for my son last night; under a paleo diet that's fine, once in a while... just don't eat that kind of stuff every day (or every week). Its not good for you. I drank a beer last weekend too.
Finally grains and legumes will make you fat then die, assuming you get enough of them (not starvation mode). If life's worth living, find a way not to fail at it. Right back to the first line, eat a carrot or something.
I eat an awful lot of salads and veggies and fruits, probably less meat than a "real american"... I just eat lots more pears than wheat.
Whole grains and legumes are pretty cheap. I don't think there is any source of protein from a whole food that is cheaper.
I would disagree on meat being overly expensive. The USDA theoretical diet claims 50 grams of protein is great. Sometimes I eat more than twice as that, or 100 grams. Its a uniquely american problem that we talk grams but sell in pounds or ounces leading to some weird ideas about portion size. I would suspect the average american thinks they need to eat perhaps 24 oz of steak to get a reasonable daily protein intake. The actual figure is a lot closer to a quarter pound. "a" quarter pound per day not two triple cheeseburger for each meal.
Broccoli stir-fry with thin slices of beef steak, mostly grilled veggie kabobs with some chunks of meat, salads with some meat on the side, that kind of thing. In the winter a homemade slow cooker mostly vegetable stew with some meat. Not meals that are 90% a slab of meat, or even 50% meat 50% carb.
I have not analyzed it but I believe I spend much more in the produce aisle than the meat aisle at the store. Sometimes in the winter my mostly fruit breakfast costs like $3 and I feel ripped off compared to what I pay in the summer, but they are flying this stuff in from another hemisphere so I guess its not so bad. If you're going to complain about expense, complain about $7 pints of organic blueberries rather than $5 little steaks because I eat more blueberries than steaks, by either volume or dollar amount. Out of season oranges flown in from Israel are another ripoff expense, although they certainly taste pretty good. Spinach is sometimes ridiculously priced also. Also sometimes bags of nuts have crazy prices like $8/pound... why decent quality walnuts sometimes cost almost as much as tenderloin confuses me.
Grains and legumes are a lot less expensive than grass-fed beef.