There are many shops selling prescription basketball goggles. Also, you can order them online in some optical shop such as Firmoo.com, framesdirect.com or sporteyes.com etc. Among them, the prescription basketball goggles at Firmoo.com are sold at cheap prices.
You can get your prescription goggles for basketball either from online or in your local optical store. However, before you order them online, you should go to have an eye exam to get your prescription. Then you can order prescription basketball goggles online with your prescritpion. Try amazon which offer prescription goggles for basketball.