I bought a lot that contains about 10 sets. I have the books and bags of pieces. This is for my own collection. I started sorting and the stickers for set 3221 are missing. The pieces are there but the stickers are not. I checked eBay and no luck. Where are some other reliable places to check?

bricklink

Yep, Bricklink.  It will be the last place you ever need to check. 

I had a similar problem this week finding a sticker sheet to replace a crumbling one, common problem with older F1 cars. On some other forum someone mentioned www.brickfactory.info having scans of many sticker sheets as last page of their manuals. They have them for 3221, so if you have a decent printer you may want to get some adhesive paper and try making your own...

Lego customer service should help Explanation the problem to them they should send a sticker sheet for you before they send it to you explan the problem personal infomation and set id you can contact them via the link on the lego website or call them

Bricklink is the best choice for buying lego part

Ebay is also a choice

I recently just purchased a bunch of pieces for two separate sets from Lego.com. The process has been smooth thus far, but a bit sad that some pieces were out of stock. You can decide if you want to use Lego.com or BrickLink, which is a bit confusing, but has many sellers and hard to find items.

 

Do some research and good luck!

I just bought a bunch of missing parts last week off of BrickLink.com ... it is actually pretty easy!!

I used toypro recently.  It's a little more expensive than bricklink, but thay are a one stop shop and had a lot of pieces I was having a hard time finding.

Does LEGO Shop at Home provide missing stuff in sets they didn't sell ?

Does LEGO Shop at Home provide missing stuff in sets they didn't sell ?

Wouldn't condone the use of it like that. Its meant to supply missing/broken pieces from a newly opened set, not an open one from years ago.