@donhat148 There are ways to verify if a seller is legit. One of the easiest ways is to initiate a short conversation. Most capable sellers won’t mind a short back-and-forth on your project. It gives them an idea about you too! If something does not feel right in a brief conversation (such as the seller is making you wait unreasonably long) see it as a red flag and move on.
You can also read the comments on the seller’s profile. What other buyers said, might give you some indication about the person. If you are trying a new seller without reviews, the first-time conversation should be a bit longer and more detailed. Rather take some time to set out your instructions clearly and ask the seller to parrot it back to you, to see if he/she understands.