What 3G phone should I buy?

Don't say I'm posting this again. Yup I'm mobile phone-maniac. Anyway, should I get a new line with M1 while I'm still doing internship? M1's corporate plan is the best among all. It's prime plan is only 14 bucks per month for 400 mins (but incoming is not free) + 300 sms. Since I already have one line with starhub which is incoming free, I think M1's prime plan is very attracting to me. Oh, caller ID and autoroaming are also free for 2 years. Every month, my hp bill shoots up 50/60 at least which is beyond my basis price of 30 bucks even though I didn't make extra 400 minutes of outgoing. So I save at least 6 to 20 bucks per month with 2 lines. And in 2 years, I can save 144 to 240 bucks. But, the deposit is $500 at M1. Is it worth? Some more I have to minus $70 fromt the saving for the time while I'll be in Japan (5*14). So I can only save 74 to 170 in 2 years lah. But, the handset prices are very cheap in M1 compared to the other 2. Some more, it's said that we can use 3G handset in Japan. So, please suggest if I should get a new line and if so which 3G phone should I buy? My preference is Sony Ericsson K800i. Don't just Nokia haha... I support Japanese brand. Some more Lee Hom endorses Sony Ericsson.

If I get a line new,

Immediate cost: $500 deposit + apprx. $200 for new handset (which is 300 to 400 cheaper than retail price) + $14 * 5 months while I'm in Japan (cos I can't suspend my line). I maybe not able to use that handset in Japan (which means it'll be slightly outdated here when I come back in Aug).

Benefits: My monthly bill will be capped at $54 (500 outgoing + 1400 sms for 2 lines. Plus, FOC for first 5 mins of video call to another M1 customer). Cheap handset.

I can only get this discount until my internship is over in Feb. So not possible to apply after coming back from Japan. haiz...