When it comes to buying affordable travel bags, there are a few features you should look for to ensure you make the best purchase for your travel needs.  Wheels: The next time you need to hustle between gates at the airport, you'll be glad you have wheels. Some travelers prefer spinner-style suitcases that can spin 360-degrees, but you can also find wheeled duffle bags and other styles of suitcases with only two wheels. Size: Be sure to pick a suitcase or backpack that's big enough for your travel needs without leaving you with too much extra space. If you want your new travel bag to fit under your seat, then you'll probably need to pick a travel backpack. Carry-on limits: Different airlines have different guidelines for carry-on luggage, so if there's a particular airline you like to fly, check their carry-on limits before buying a new suitcase. The TSA doesn't have guidelines on carry-on luggage sizes, but most airlines require carry-on bags to be no larger than 22" x 14" x 9". Locks: Expensive luggage sets often come with sophisticated locks; however, some of the best budget luggage sets also feature locks. Make sure the locks are described as TSA locks, as the TSA requires that all luggage locks must be accessible to TSA employees.