If you're talking about like... you live in a medical marijuana state, and a properly licensed dispensary is on wheels (yes these exist in California), go for it. Couldn't hurt to try, other than not having a strain you want, or having slightly higher prices or whatever.
If you're talking about like... you found a website in a non-medical state that says it sells "weed", don't do it. It's either not legit, a RC chemical, or a horrible set up waiting to happen.