I'd trust HealthCabin or Heaven Gifts more. They have mega KR8 batteries for ~$12 and shipping starts at $15 for EMS, so the price is comparable but their reputation is established here. HealthCabin also has % discounts with coupon codes in their subforum so the price is actually lower.
Also keep in mind that the sellers domestically who charge more are providing two things:
1/ warranties that are easier to take advantage of (faster communication and easy re-shipment),
2/ batteries that have improved features from the standard KR8 manuals. (The V4L and Nhaler KR8 mega batts have much longer cut-off times than the 5 seconds you'll get with these standard ones.)
Also, if all you want is the battery for now,
Bluegrassvapor has the standard (5 sec cutoff) KR8 mega batts for $15.50 with free shipping. And they're also domestic, so less waiting.