Congrats on picking up the Liberty. Did you get the manual or auto?
If I was in your shoes the first thing I would do is check the rotors and pads that came with. After 50K kms there are likely to be coming to the end of their life, well at least the pads. Stock rotors are average at best. Obviously a bigger brake package would be a good upgrade if you can afford it. Next I would look at changing out the stock front and rear sway bars to whitelines or similar. Stock sways are tiny and hollow. If you can get a used set of sti pinks and bilsteins for $800 then just do it. I got rid of the sti pinks due to the bobblehead effect but they are still way better than the stock springs. Leave the stock airbox and intake and just get a HKS or similar panel filter though. Once you have that sorted then I suggest its time to look at the exhaust and lastly get her over to ASG for some Verso magic.
Have a look at Jimmy's or my thread as there is plenty of good information on mods for Libs there. Also suggest you join up over at
www.liberty.asn.au as there are some good vendors specifically for Libs there and a good post your mods section.
Good luck and enjoy