Most will survive solo. Occasionally dwarf hamsters raised in a group and handled frequently can become lonely and die if left alone. Most petstore hamsters are so young and infrequently handled that they adjust fine. The only ones we've had that actually had issues going to a home alone were hamsters we had bred and kept to adulthood with their same gender siblings.
If you want to get gerbils I suggest you check out the ags (american gerbil society) website and stop by one of the rodent shows. There's one in missouri every october. I don't keep track of the rest since they aren't near me. Petstore gerbils and dwarf hamsters are just plain scary sometimes. They are poorly bred, poorly handled, and often agressive or defensive leading to lots of bites and a very long time to tame. We raised some absolutely wonderful and very friendly gerbils and hamsters growing up but we've never handled a good one in stores and the one we had from a local petstore attacked anything put in it's cage whether it was fingers, food, or plastic/metal objects. My mom loves gerbils but tells everyone not to buy them these days because so often all you get is a nippy critter you have to chase around the cage. Go with a breeder and you will be amazed how tame these little rodents can be. My gerbils would help me clean their cage by carrying the dirty bedding to one corner whenever I got out the little trashcan and scooper I used to empty it. They also were found sleeping on my pillow a few times when they escaped during the night. My sister's dwarf hamsters would pile on the door day or night anytime they heard someone in the room just begging for attention or treats.
