Storage Solutions New HDD or enclosure???

[evilwit]

Hey guys I have a Seagate Go Flex 1 TB external hdd which I bought in 2011.At that time it came with a USB 2.0 adapter which can be later upgraded to USB 3.0 for faster speeds.So now I am unable to find a usb 3.0 adapter.And also there are many scratches on the outer casing of the hard disk.As my hard disk is working fine,I am thinking of removing the outer case of the drive and replace it with a USB 3.0 enclosure which costs around 800-900 bucks.But I dont know whether it will work or not?And secondly I want to ask you guys if its possible to sell it for around 2500-3000 bucks and then add some bucks (thats is around 800-900 bucks)and buy a new one?In this way i will also get warranty.please reply and help