To find a reliable supplier, start with evidence of deliveries for products like yours.
Look for the same kind of product
If you are buying acrylic display stands, ask for display-stand project records. For example, evidence of a 500-piece bonded-display order tells you more about project fit than a few photographs of laser-cut samples. Check what was actually made and delivered.
Follow one project from drawing to packing
Ask for drawings, sample photographs and packing photographs from the same project. A rendering shows the design intent; close-up photographs of the actual part let you examine bonded seams, edge finishing and assembly quality.
Start with a manageable trial
For a first order, consider a small batch to check the result. For example, inspect the appearance and packaging of 100 pieces before discussing a 1,000-piece repeat order. A staged purchase gives you a chance to assess the work before committing the full requirement.