Where to buy adjustable dumbbells: These retailers still have stock

Bowflex SelectTech 840 Kettlebell: was $199 now $119 @ Amazon
The Bowflex 840 Kettlebell can be used to perform a wide variety of total-body workouts. The adjustable kettlebell features weights that range from 8 to 40 lbs. It also sports an ergonomic handle and a weight selection dial that lets you pick the weight you desire. 

All-Purpose Solid Cast Iron Kettlebell: from $12 @ Amazon
Amazon has stock of the Everyday Essentials Cast Iron Kettlebell with prices starting from $12.50 (for the 5-lb. kettlebell). It has a textured wide handle for better gripping and a flat bottom to prevent rolling. It's available in 5- to 50-lb. increments. 

Skonyon Adjustable Dumbbells Set: was $199 now $89 @ Walmart
The Skonyon Adjustable Dumbbell is great for beginners. Its weight can be adjusted to 2.5, 5, 7.5, 10, and 12.5 pounds. This price is for a set (two dumbbells). 

Aduro dumbbells (pair): from $24 @ Amazon
Amazon has stock of various Aduro dumbbells with prices starting at $24. The dumbbells feature a coated exterior and a hex shape to keep them from rolling away. They're available in pairs of 5 lbs, 7.5 lbs., and 10 lbs. 

NordicTrack Adjustable Dumbbell Set: $99 @ Dick's
Need a basic, reliable set of adjustable dumbbells? This set of NordicTrack dummbells can be adjusted from 2.5 to 12.5 pounds. The price includes the full set (two dumbbells). 

ProsourceFit Dip Stand: was $77 now $49 @ Amazon
If you can't find where to buy dumbbells, use your own body weight. That's precisely what this dip stand allows you to do. You can use it for dips, under bar pull ups (lying pull ups), and more. Even better, it's now on sale. 

Weighted Workout Bars: $22 @ Walmart
From bicep curls to squats, this weighted workout bar can be used to perform a wide range of exercises. The bar is made of steel and has a padded foam surface. This deal is for the 5-lb. bar. 

NordicTrack SpeedWeight: $199 @ Best Buy
Once impossible to find, Best Buy once again has stock of the NordicTrack SpeedWeight dumbbells. These adjustable dumbbells can be tweaked to range from 2.5 to 12.5 lbs. each. The dumbbells come with an easy storage rack to help keep your workout space tidy.

Deiris Water-Filled Dumbbells: $45 @ Amazon
Although the Deiris Water-Filled Dumbbells were designed for travel, they can also be used for everyday workouts from home (especially now that everyone's having trouble with where to find dumbbells). The Deiris dumbbells are filled with water and have a max 45-pound weight. This set includes two handle bars, 8 dumbbell balls, and all the necessary accessories to keep the dumbbells secure. 

MaxKare Power Tower Stand: $149 @ Amazon
MaxKare Power Tower uses your bodyweight to let you perform pull-ups, dips, and pull-up crunches. The stand supports all weights up to 380 lbs. It stands 7.2', which makes it suitable for anyone measuring 5.2' to 6.6'. 

AmazonBasics dumbbells: from $29 @ Amazon
AmazonBasics offers a wide variety of cheap dumbbells in weights ranging from 3 pounds to 20 pounds. The neoprene weights cost as little as $29, although keep in mind the cheaper dumbbells tend to sell out rapidly. 

ProForm SpaceSaver Dumbbell: $144 @ Amazon
The ProForm SpaceSaver Dumbbell is a compact (single) dumbbell that can be adjusted up to 25 pounds (in 5-pound increments starting at 10 pounds). 

Weider 300-lb. Weight Set: $259 @ Sears
Weider's 300-lb. weight set is perfect for any type or workout from squats to shoulder presses. Although it's not technically a dumbbell set, this kit includes a 7-foot 45-lb. bar, 2 spring collars, and 14 plates. The plates come in pairs and weigh from 2.4 lbs. to 45 lbs.  

JAXJOX KettlebellConnect: $229 @ JaxJox
JAXJOX makes a variety of smart fitness devices. Their Kettlebell Connect is an adjustable kettlebell that lets you choose one of six weights ranging from 12 to 42 lbs. (weights are selected in 6-lb. increments). Hard to find online, JAXJOX has it in stock at list price.

BodyBoss 2.0 Home Gym: $199 @ Amazon
Can't find dumbbells? The BodyBoss 2.0 is a great alternative that also happens to be Amazon's best-selling home gym. It includes a base, bar, bands, straps, handles, and more to let you target every muscle in your body. The package lets you perform upright rows, rear delt flys, squats, and more.