I've been looking through a lot of places and i've found the cheapest luggage tags at
http://tags.idcardgroup.com/productdetails.aspx?item=1840-620 you have to buy the loops separatly, but it still comes down to being pretty cheap. Also, I'm going to use vistaprint.com for the business card inserts. I think it'd be easy to do by yourself at home, but we're using a picture of us for the front of the luggage tag that I think needs professional printing.
We're going to use these as save the dates....any suggestions/experience with shipping options? According to USPS you can ship in a regular envelope for reg. stamp postage as long as the weight is under 3.3 ounces (I think one luggage tag weighs 1.7 ounces, so 3.2 for two) and is under 1/4 inch in height... I'm hoping regular mail will work if I don't attach the loops, but we'll have to see. Good luck!