I’m always banging on about how I’ve a backpacked around South America – and various other places – but the truth is that I don’t actually do much backpacking… Backpacking is where you disappear into the mountains, *living* out of your ‘pack, i.e. carrying a sleeping bag, tent, food etc. and walking 10-15 miles a day.
My version of ‘backpacking’ is nowhere near as hardcore, I grab my pack from the airport luggage carousel, put it in the back of a taxi to the hostel, the next morning I walk a few blocks to the Bus station and onto my next stop… The longest I have ever walked with a full kit backpack is about 4+ miles when, in a fit of peak, I walked into town from Nouadhibou railway station (Mauritania) rather than pay a massively inflated taxi fare.
Which brings me onto the first thing that you shouldn’t buy: A top-end backpack.
An expensive pack will usually have an aluminium frame to balance the weight and thick padding to sit in just the right spots on the users’ shoulders & back, great for high mileage hikers, but a complete waste of money if your pack spends most of it’s life strapped to the roof of a bus.
My first ever backpack was purchased second-hand from a local army surplus store for £10. For my 2011 Africa trip (3 months), I bought a 65 litre olive-green military pack from ebay, a snip at £29.
My other questionable purchase ‘pet-hate’ is high-end walking boots and/or Jacket – for pretty much the same reasons – unless hiking is a core part of your trip (in which case you’ll probably already have your own kit?) your existing shoes/boots/trainers will be fine for general travel use which includes an occasional lengthy trek into the hills.
Prepping for independent travel will usually require you to splurge some cash, my advice is to bring your old, well-worn clothing/kit away with you and avoid buying expensive items that won’t see much use once you’ve returned home.