Your Ziplock bags are not for one time use only.  You must wash & reuse your Ziplock bags as often as possible.  These bags are very expensive.  Ziplock bags must be used at least a few times.  Recycle your ziplock bags if you are done with them. 

This is how I wash my used Ziplock bags.

1. Turn the bag completely inside out.
2. Use dish soap and sponge to wash "outside" ("outside" which used to be the "inside")
   • Lay the bag flat on the kitchen sink and scrub it with plenty of detergent (pay more attention if the bag used to hold blood).
   • Rinse inside the bag briefly ("inside" will become "outside" later)
3. Dry the bag as is (bag is still inside out).
4. After the bag is dried, turn the bag inside out to its original form.
5. Personally, I do not worry about the outside of the bag. 
   • I only care about the inside where it will touch the food.

Drying….