Not all lenses come with prescription but a lot does nowadays, so you shouldn't have too much trouble to find lenses in your prescription even on most big lens stores.
I can personally recommend LensVillage
, good selection, customer service, authentic lenses and you get free overseas shipping if you buy for 40 dollars minimum. Shipping tends to take 2 weeks on average. Discount code SAMURAI15 gives you 15% off on pretty much anything too.
I've been buying from them for 5+ years and never had any issues; I know a person who got a defective lens and when she wrote about it they sent her a replacement lens with no additional costs.
If you have light blue eyes like me you might want to check out my list of lens reviews here
as I've done a lot and of many different colors. Good luck and feel free to ask me if you have any further questions or want lens suggestions for a specific character!