You can get sticky barcode labels printed for your barcode, which can then be manually stuck onto your product.
Unfortunately, this is not a service that we offer in Singapore at this stage. Hence it would help if you talked with label printers in your area. They should be able to arrange this for you with little difficulty.
Union Labels can provide labels in various sizes at reasonable prices. They can do custom dies to cut labels to your preferred size or use a standard size for labels that would be more economical. Talk to them or talk to another company in your area.