Cost effective way to self print stickers? Besides a label maker?

I don't think you can produce good quality stickers by yourself, without a investment in hardware.
It also really depends on what kind of stickers.

There are many many variations, custom shapes, kiss out stickers, clear stickers, transfer stickers and more.

If you want cheap ones, you can get pretty good quality from china.

Wes Bos is ordering his stickers from (said that matte ones have stickermule quality).
More info in this thread:…

I have a couple of those on my laptop. Pretty good quality although on one (of the matte) a plastic like film is coming off. I think it's been on there for 6-9 months.