Maybe further than you'd want to drive, but three places spring to mind in Boynton area -
Boynton Diner (Federal Hwy at Woolbright): they have an awesome array of breakfast items - pancakes, French toast, fritattas, 3 egg omelettes, breakfast sandwiches, etc. I have a friend who eats here every day in the season, and he swears by it. They extend the menu with specials that look just out of this world good. Lunch is also killer - Man v. Food portions. Try the Lake Worth or Cuban Reuben.
- Hurricane Alley - Federal Hwy in "downtown" Boynton, wonderful oysters ($6 a doz during 4-6pm happy hour). Must try the smoked fish dip, but just about everything is excellent here.
- Dune Deck Cafe, located just north of Delray in Lantana/Hypoluxo on A1A, just a great place for lunch, right on the beach. We went for lunch but they also serve a great breakfast menu. We were strategically positioned near the kitchen and saw a lot of items go out. Everything looked wonderful, especially the salads, and BIG.
Great choice for casual cheap food with a view and decent people-watching. Not open for dinner.
All offer large portions, great tasting food, god service, and low/moderate prices.