depends.....you can buy the 2.5 -> 3.5 IDE converter from Maplins for £4.99
add an old PC hard drive(that you may or may not have hanging around).... 8 gig, 20 gig.. whatever!!
I gather the OS3.9 is a bit naughty, you take the risk if you want.
But looking at it.... it's a fiver postage, obviosuly he's included his paypal fee in that and also it's a starting bid of £7.50.... how high is that going to go??
Your choice buddy!!