Just my 2 cents to help save cost IF a few factors fall into place.
If you have access to Sams club you can get 25 6x9 for $5.28 ( Demographics fluctate price im sure but prolly not by much)
Dollartree~Can get 2 for $1
Walmart~2 for .99 ( demographics fluctate prices)
Packing Tape (only needed if you dont buy self sticking labels)
Walmart~Goto office supplies and there is a 60 yd roll for $1.49
Dollartree~ 40Yd Roll for $1
Self sticking labels (make sure you choose label only)
Walmart~ Avery mailing labels #8126 $16.99 for 25 sheets =50 labels
Ebay~ I do a ton of ebay selling and this is the best bet I get about 200 labels for $10
Of course paypal or amazon for shipping.
My last advice is use the self sticking labels. Saves time and money. Also pick up a cheap food scale for weighing packages. Way cheaper than a digital postal scale and just as accurate.(check thrift stores for these I paid $2 for my scale and goes up to 4 Lbs.)