Free Contact Trials!?

Hi, I was recently at my optometrist and I was fitted for eye contacts. I got some random Ciba Vision contacts at first and they were extremely uncomfortable. I then asked for a trial pair of Air Optix Aquas and Air Optix Night and Days. They said they didn't have Night and Days in stock and he gave me Aquas. I don't think they are aqua's because he took them out of the case and I saw a picture of Aqua trials, it says Air Optix Aqua on the cover, while these just say Air Optix. So I'm not sure what to do. But my question here is, If I get my prescription written out, can I go to Walmart/Costco/Lenscrafters/Etc. and ask if I can get a free trial pair of Night and Days or Acuvue Oasys? Would they actually give them to me, or would they say you have to be checked by our optometrist in order to receive them? Thanks.