DIY stickers!
This is the cheapest but most time consuming way to get stickers, pretty much the LFS of the sticker world.

Supplies
https://www.amazon.com/dp/B01DJBMLV2/ - Blank sticker paper, 100 sheets, 8.5" x 11", ~$0.13 USD per sheet.
https://www.amazon.com/dp/B00007E7D2/ - Self-adhesive laminate, to protect your stickers, not required but it helps. 50 sheets, 9" x 12", ~$0.28 USD per sheet, don't buy the two pack.
https://sbw.dhl-usa.com/SupplyOrder/SupplyOrderList.asp - Free sticker paper and laminate if you have a DHL account. The "WebShip, CorporateShip Labels" are black half-sheet sticker paper, and the "Plastic Waybill Sleeves" have a clear plastic adhesive backing which can be used for laminate. Both can be ordered in bulk for free.

Programs
https://inkscape.org - Vectorization program
https://krita.org - Image editor with advanced paint tools
http://www.getpaint.net/ - Image editor with basic paint tools
https://www.gimp.org - Image editor with paint tools


1. Find or create images for stickers you want to print.

2. Create blank image with the same aspect ratio as the paper you're using, multiply the size of the paper in inches by the dpi you want the stickers to have.
2a. For 8.5x11 (8'6" translates to 8.5') paper and 300dpi you would create a blank document at 2550x3300 pixels.
2b. I use 960dpi on all of my prints, but I'd recommend 300 as a bare minimum and 600 as ideal. Anything over 1200 is useless, and may decrease the quality of the finished sticker depending on how your printer scales images before printing them. Check your printer's dpi to see what sort of print resolution it supports.

3. Import and arrange the images you want to print into the blank document, to figure out how big the stickers will be when printed, use a ruler or sheet of paper to zoom your document to actual size.
3a. Give your stickers breathing space between each other, remember that you're going to be cutting these out by hand.
3b. Keeping 3a in mind, use the whole page if you can. Duplicate stickers for backups if you have room to fill, printing a second time on partially used sticker paper can be a pain in the ass. If you're not confident in your scissoring abilities, add a few test stickers to practice with.

4. Do a test print on some regular printer paper, do these in black and white to save colored ink.
4a. If the test print cuts off the sides or top and bottom of the sheet, check the aspect ratio of your image. If you divide the width of the image in pixels by the width of the paper, and the same for the height, both numbers should be the same (imageW / paperW == imageH / paperH). Also check your print settings to make sure it's set for the proper size of paper.

5. If the test print goes perfectly, switch back to colored ink and insert your sticker paper. Print them.

6. Let the sheet dry for about 5 minutes to prevent ink smudging.

(OPTIONAL LAMINATION) Laminate application is best seen rather than read, I'd suggest looking up a youtube video for this.

7. Get your scissors and separate each individual sticker from the sheet. Don't start fine cutting until every sticker is on it's own.

8. Take it easy. Cut holding the sticker in your off hand and the scissors in your dominant hand. Don't grip the sticker too hard, it may warp the paper or smudge the ink. Using nitrile gloves will prevent sweat from damaging the sticker before you've even placed it.
8a. Leaving a border of whitespace around a sticker will lessen the impact of mistakes and usually makes stickers look better anyways.
8b. If you know what you're doing, an exacto knife can be used in instead of, or in additions to scissors. They're better for getting at tight corners, but for long straighter cuts they can be less effective.

9. Most sticker paper has slits cut in the back to help peeling, but if you've printed a sheet with a lot of stickers some of them may not have been printed on top of one of those slits. Fingernails help.

10. Stick with the stick.