Deffinitely get the Baby Trekker.
I've tried tons and tons of different slings/packs and once I got my Trekker I've never used anything since.
My dd was a preemie and there was even a added strap for "'extra tiny' little ones, so it was just perfect for me. Now my dd is 10mo old and still rides around in it and falls asleep almost everytime.
They are so padded and comfortable.
You can strap them on any way you want.
They're easily ajdustable for 'dads'.
They're machine washable.
and you can nurse in them too!
I found mine used on another baby message board so I'd look around, try E-bay I've seen them there too.
The only ONLY
complaint I have, is that with all the padding it gets kinda warm wearing it, but here in Washington, I don't have much problem with that. Depending on where you live it might be uncomfortable to wear if it's really hot outside.
Save up for a good one and you wont have to buy any others
You wont be sorry!