For beginners, Ben recommends trying five to 10 pounds for light weights, 10 to 20 pounds for medium weights, and 15 to 30 pounds for heavy weights—or simply starting with five-pound weights for each exercise and working up from there.

If, however, you're a beginner set on the idea of having fixed dumbbells in your home gym, then we recommend the 150-pound dumbbell set from CAP Barbell. These hex-shaped dumbbells come in five pairs—5, 10, 15, 20, and 25 pounds—and with a dumbbell rack, all for under $400.

Cheap Dumbbells Whether you are new to weight training, or an expert, dumbbells are perfect as a full-body conditioning tool. They can be used to target a wide range of muscle groups, help you build strength and muscle, and as part of a Circuit or Cross Training workout, they can also increase stamina and endurance.

Do they offer the same physical benefits? For the average person, free weights offer many of the same benefits as machines, plus some. While you can typically lift more weight in the same exercise on a machine due to their fixed nature, free weights give you more bang for your buck in terms of muscles worked.