I can send you some spearmint and peppermint plants for free (bare root) if you pay for the postage. I was going to give them away anyway.

If you want a physical location to shop at, you'll have to share the general area you live in. But for online shopping, you can try:

Richters
Horizon Herbs

FataMorgana

Yes, do try to get someone to share some mint with you for postage or maybe there is someone right in your area. Mint grows like crazy and thinning doesn't hurt anything so the only problem with sharing (other than possibly some department of agriculture restrictions in some areas to prevent spread of some pest) is the trouble to dig up some and mail it.

My mint is in pots.

Walmart. Lowes and Home Depot has several varieties of mint.

i have chocolate mint

beware, if you have consistently moist soil, it can be invasive.
if it gets fairly dry on a regular basis, its not bad though.
just an FYI...

In my area mint is widely available at nurserys and grocery stores. Territorial Seed Company has them available online as well, but the deadline to order for this year is coming soon. I grow almost everything, including spearmint, from seed, but they did do a good job with my Bay Laurel and they were very affordable.