Your instinct is right – the closer you are to Calle Larios and the cathedral, the more you pay for the location. Walk five minutes out and it changes.
For lunch, the streets around the Atarazanas market are solid, and the market itself has a couple of stalls doing fried fish and a glass of wine at the counter. Calle Carretería and the Lagunillas side of the Merced have small, plainer places with a menú del día around €13 to €15. For tapas in the evening I would point you at the bars near Plaza de las Flores and Calle Comedias rather than the main drag.
If you want the classic espeto – sardines grilled on a skewer over a boat full of embers – that is a short bus or long walk east to Pedregalejo or El Palo, and it is worth the trip on a warm evening. Our
Málaga food guide has the specific spots. Are you after a sit-down meal or a stand-at-the-bar tapas crawl?