IMHO, the properties that run the "best" specials (i.e. the cheapest) are:
1st Choice, Never Disappointed @ Compass Cove - excellent amenities, quiet southern location, rooms from Condos to hotel rooms (we're staying OF effec. 6/29-7/23 @ $1000) We really like this place.
2nd Choice, Landmark Resort - good amenities, rooms of average to slightly below average quality. Last time we stayed there were several very large family reunions, even had their own tour buses! Think they were over the stated occupancy levels in their rooms, that strained the use of the pools.
Atlantic Tropical Winds or Captains Quarters North (both owned by the same people). A step below the above two; older, outdated, also in south area.
There is a very nice Days Inn, now part of the Grande Dunes in the Northern section of town (79th Street, N). If you just need an effeciency they run around $100 in August.
Myrtle Beach Live is a great source for finding deals on rooms (look under accommodations section and most of the hotel & condo web sites are listed.
We LUV Myrtle Beach!!!!! We've been going back for almost 30 years, think the 70 miles of beaches are heaven. Have a great time.