Baby bjorn was out of our price range too but I looked really hard and tried on heaps of different ones at the baby shop. The lady was really helpful and pionted out things with some of them that may have been a bit cheaper but would've made them uncomfortable to wear and such. we ended up getting an 'Infantino" and I was really happy with it. It's got wide jelly like straps so it doesn't hurt your shoulders and is pretty easy to get on and off. I should piont out that when I tried all off these carriers I had ds with me coz I waited until he was a few weeks old or so. I don't remember exactly how much it was but I have a feeling it was about $60 or $80 so pretty middle of the range.
Maybe check out ebay or the quokka too coz they often have good ones reasonably priced and you should be able to check them out before buying.