I am also at the other end of the spectrum of those "my rucksack was only 300$" posts - they just make me shudder ... apart from anything else I must admit that I would feel guilty walking past anyone poorer than me and me wearing enough money in kit and clothing to get them out of debt!
So .... my boots are cheap Hi-Tecs (30 euros I think) and all my 'out there' clothing and so on is from charity shops or verr cheap. I met an English girl at .. errmmm ... well, somewhere .. just outside Burgos .. and she had no sleeping bag at all, would just find a blanket and go to sleep. She told me it worked most of the time and she had only had one or two cold nights....
If you were to wear a monastic habit you can take it off, reverse it 180 degrees and use it as a bed cover
Cheapest (and lightest) way to go is with just a sheet/liner.
Asda and Tescos are both doing very cheap sleeping bags - but not wildly light ... you can save on a pole if you carry a pocket knife by making one from a stick in the first wood you walk through - though they are truly cheap now and I like my pole. I do prefer a poncho to a coat for coolness and free moving air (who cares about the legs? they are waterproof!) and a fleece (charity shop again) under for warmth .... though, on the other hand, the recent weather would have meant me buying more warm kit ... but still the cheapest ....
Another thing to remember - or realise - is that we do not own possessions - possessions own us. If they are expensive then we will fear them being stolen so then we will fear strangers ... we have to worry about them all the time - it is really a fetishism, consumer fetishism ...
And deeper down ... there is only one real currency on this planet, it isn't dollars or pounds or euros or whatever, it is time - irretrievable segments of your life.
If you buy a rucksack for £150 and you earn £75 a day then you have just given away two days of your life for the 'pleasure' of wearing an expensive rucksack. Looking cool at the traffic lights in a new car that will be in a scrapyard in just a few years and that cost you £15,000 isn't as cool as you think it is as, if you earn £15,000 a year, then you have just given away one whole year of your life for that dubious pleasure - in the truest sense it is a pact with the Devil .....
what a waste of a life! - so, I agree, go functional, but go cheap - spend your life currency on important things ... don't you agree?