I buy my price tags at Walmart, I get the orange and the green florescent ones, a set of big and a set of medium. I cut off the string and thread yarn or narrow ribbon through the hole in the tag and tie it onto my projects. I think that looks less "retail" because I only sell handmade items. And if it's a holiday sale, I'll draw a little holly w/berries, or little hearts, or something else festive on the tag.
A lot of times people will ask me for my name and phone number when they are interested in an item but can't purchase it right away so I always have cards that I've made up on my Excel program with that information. I make them big, around 3x2, if they are too small they are easily lost, and I print them out on florescent paper so they are easy to spot.
If time permits, I also make custom tags like Belmer, using my Excel program. I put on an item description, the price and my initials (sometimes I'm in a sale where your stuff is spread around so I put on my initials or my sales number if I'm assigned one). So a tag might say "luggage handle covers/stocking stuffer/$1.00/llw"