MB Food
Check out Restaurant Row on US 17 north of town. Chucks is excellent, and two of my favorites are Chesapeake House and Chestnut Hill. A little more pricey is Cagneys.
Downtown Myrtle Beach is Nybil's. An excellent restaurant, the owners ran Nybil's on the pier in Surfside until a lease situation caused them to relocate. The food is excellent and in your price range. It is on US 17 Business just north of the old mall location and on the same side of the Hwy.
There are some good chain restaurants, also, i.e. Bonefish Grill, California Dreamin'.
If you want to really splurge and go all you can eat, try the original Benjamin's on Restaurant Row, as well.
You won't go wrong with any of these choices.
MD