I got a "new" Huawei T-Mobile Sonic Hotspot (the E587) on E-Bay, got it unlocked, all in 60 bucks or so with no SIM lock... I now own this device
Then I now just get a SIM from these guys:
http://www.keepgo.com/
Tend to have multi country trips lately so I have a SIM + MiFi ready to go before I leave. Using Keep Go's international unlimited SIM. NOT cheap but allows me to avoid the hassle of multiple SIM's for each country and top up issues + waiting on rental pickup for Japan MiFi in hotel. I land in Haneda or NRT with a working MiFi right when I'm on the ground, no return needed.
The SIM Keep go sends you is yours and they deactivate the SIM, NO return of SIM needed
Keep Go provisions either AT&T SIM's or Vodafone Germany SIM's; seems to work OK; extra latency as APN redirects back to US or Germany. Flat rate with fair usage (500MB a day). The single SIM works in multi countries if you order international multi country. Meaning you can take your same MiFi and the SIM from KeepGo and travel anywhere including Japan and use it right away, no swapping SIM's or having to carry additional MiFi's. Used it so far in Japan, Taiwan, Singapore, Malaysia, South Korea and China - since the APN goes back to Germany or US it avoids China filtering also.