That said, kneejerk after using it is: price is a challenging anchor, because food is not uniform. I’d be curious if users are more interested in “under $10, ignoring all else” or “a better deal than comparable” - though, there’s a lot of subjectivity in that.
Gasbuddy works because 1 gallon of gas = 1 gallon of gas, so price is a useful anchor.
$5 for sushi at one place could be a bad deal, while a great deal at another place.
An $8 steak would be cheap. An $8 hot dog would be a ripoff.
I’d be skeptical of restaurants luring people with a single cheap item, or about quality/portion changes.
All this said, Ikea is known for designing furniture _around_ the price their target customer thinks a table should cost. Restaurants are likely (hopefully!) aware of where these price thresholds are for their customers … and your site could be an interesting way of sending them a different type of customer than they’d historically targeted. Or, allow them to refine an offering to maximize profit at the $10 price point.
As others have said, engage restaurants and make them part of the equation. They’re not your adversary.
In short: cool! Do lots of experiments and research!