Reproduce my statue to sell?

I sincerely doubt the Buddha will mind you making images of him. No one else would be able to file a copyright infringement if your work is in a style like the very very old design. Only a fairly recent work of art would even likely be covered under copyright law. Certainly copyright law does not apply to thousands of year old religious art.

Copyright law does not restrict your copying of works that are in the "public domain", meaning works that have no copyright.

Under US copyright law (and similar in other places), copyright has a limited duration. Anything published in the USA prior to 1923 is "public domain" (not including sound recordings). In most other countries, copyright expires 50, 70, 90 or 100 years after the death of the last surviving "author".

If you're looking into things 1500 years old, I wouldn't worry about whether the sculptors are going to sue you.