I have a 1 yr old Samsung Jet cellphone. It's full touch so no T9 keypad or QWERTY pad which I prefer. I don't really like full touch phones.
I saw last August 2010 the newly released Xperia X10 mini PRO which is really tiny, has touch screen function, on android OS, and most of all: a slide out qwerty pad! I've never had an android phone before so it's something that I want to try out too.

Anyway, I've decided to trade my old Samsung Jet for a used xperia x10 mini pro because the brand new one is too expensive for me If I bought a new one, my jet would be useless so might as well trade it.

Brand new Samsung Jet mall prices are about 13-14k.
Brand new Xperia X10 mini pro mall prices are about 15k.

Questions:
1. If I were to trade my 1 yr old Jet for a sightly used x10 mini pro, how much cash should I be adding if need be?

2. Should I trade? Or is it better to just sell my Jet and save up the remaining amount for a brand new X10 mini pro?

3. or sell my Jet and buy a 2nd hand x10 mini pro?

4. If I should sell my Jet, how much should be a reasonable price for it?


Hoping for good replies.