The SME's price-based advertising is drowned by their larger budgets even though their prices may be lower and their quality equal or better.
Remember, in most categories prospects don't know the price of anything until they need it and then they price compare on-line so infrequent price-based advertising will not change perceptions.
So here's an alternative: memorably prove your ability to price lower.
For 15 years one of my Stooges colleagues successfully promoted a car dealership located a half hour's drive out of a major city on the premise that "Out here overheads are lower which means better prices for customers." It's believable. Prospects know they sell the same new cars as the city dealers and they also know that city property and rates are much more expensive.
Here's a small tyre dealer who used his lack of customer facilities to defend his lower prices.