Molly:
The stroller - if it's still in the box - return it to the store if you can. If not - $75. List it on Craigslist for $100 and tell people OBO - I wouldn't go lower than $75 for it.
baby Swing - technology changes as do the safety standards - I would probably list it on craigslist FIRST for $75. $50 at a garage sale.
Bedding - ebay baby - ebay - yeah - you'll lose 9% in final value fees - but you will most likely get more money for it there than you will at a garage sale. I'm bad - I bought a set of baby bedding at a yard sale for $20 - it looked brand new. Oooh man - i can't remember the brand - any way - it was missing the "lovey" - I called the company bought the matching one for $40 - sold the set on ebay for $220. So I had a $60 investment and made $140 off it.
The portable swing? $20.
I would try craigslist first. Then work on ebay. If you need help - ask!! I'll do what I can to help you. If you advertise your garage sale - with pictures and prices of items - people will come prepared to spend $$$..ALSO - if you have a smart phone and a paypal account or not - you can accept credit cards!!! It's a trip!!!