For non-credit card purchases, you can purchase 
an IPMO to Japan for $3.25 and then spend $5 to 
send the IPMO via Global Priority Mail Small 
Envelope (3-5 day delivery).  That's a total of 
$8.25 to send payment if you're sending less than 
$700 (additional $3.25 for each $700 increment).

BidPay is fine only if you need to send $500 AND 
if the seller accepts payment via Western Union.  
A lot of sellers only accept IPMO from the USPS.

You can send cels to Japan for $11 ($13 if over a 
pound) in 3-5 days via Global Priority Mail, but 
this would not include any insurance or tracking.

To send cels to Japan via EMS would cost $21 ($25 
if over a pound).  This would then include 
insurance and tracking.

I really haven't had any negative experiences so 
far (then again, I live a few minutes away from 
one of the main USPS distribution branches).  The 
fastest I've ever done an international 
transaction with IPMO is 7 days (sent out payment 
on Monday and received the cels the next Monday).

Later.